A team from University College London in Great Britain and dr. Gašper Kokot from the Complex matter department at „Jožef Stefan“ Institute have published an article titled Fabrication of High-Aspect Ratio Nanogratings for Phase-Based X-Ray Imaging in Advanced Functional Materials. Diffractive optical elements such as periodic gratings are fundamental devices in X-ray imaging – a technique that medical, material science, and security scans rely upon. They developed a new method for lamellar structure fabrication with nanoscale pitch and microscale height with aspect ratios of more than 40. Their excellent diffractive abilities were demonstrated at a synchrotron facility. Besides succesfull aplication of these structures in the context of X-ray diffraction gratings, they theoretically explored physical limitations of the method and stability of such structures in general. Production of such lamellae is important for a range of applications from sensors, batteries, solar cells, superhydrophobic surfaces to mechano-bactericidal materials.
Researchers from the Department of Complex Matter Mojca Vilfan, Borut Lampret, Žiga Gregorin, Luka Cmok, Patricija Hribar Boštjančič and Alenka Mertelj, Darja Lisjak from the Department of Synthesis of Materials, Andrej Vilfan from the Department of Condensed Matter Physics and co-workers from abroad have published the paper Spontaneous chiral symmetry breaking and lane formation in ferromagnetic ferrofluids in the journal Small. Ferromagnetic ferrofluids are suspensions of magnetic nanoplatelets in fluids, which at sufficiently high concentrations exhibit a ferromagnetic phase. Exposed to an oscillating magnetic field, under certain conditions, a striped structure is observed under polarising microscope, which was explained as formation of magnetic domains. Spontaneous chiral symmetry breaking leads to nanoparticle rotation and consequently to the generation of fluid flow which, despite the uniformity of the external field, flows in opposite directions in neighbouring stripes.
The paper titled Dynamics of domain walls in ferroelectrics and relaxors, which was recently published in the Journal of the American Ceramic Society by Mojca Otonicar, Mirela Dragomir and Tadej Rojac from the Department of Electronic Ceramics, has been selected for the 2023 Edward C. Henry Award. This award is given annually to an outstanding paper reporting original work in the Journal of the American Ceramic Society or American Ceramic Society Bulletin related to the topic of electronic ceramics. The awarder paper collects the main results of the research activities of the laboratory related to the origins of the piezoelectric responses of selected ferroelectric and relaxor-based ceramic materials. The focus is given to the dynamics and structural aspects of domain walls as the dynamic interfaces that are often the major contributors to the electrical and electromechanical properties of these technologically important material classes. The journal cover of the issue in which the paper was published was designed by the authors in collaboration with Mito Gegič.
Today, probably more than ever, we face a growing need for robust metal preservation and establishment of both greater sustainability and a circular materials economy. Prof. Ingrid Milošev of the Jožef Stefan Institute's Physical & Organic Chemistry Department and Prof. John R. Scully of the University of Virginia's Department of Materials Science and Engineering have published a perspective paper, Challenges for the Corrosion Science, Engineering, and Technology Community as a Consequence of Growing Demand and Consumption of Materials: A Sustainability Issue in the September issue of CORROSION journal intending to bring awareness to the material science and corrosion community that the growing demand for engineering metallic materials required for our increasingly technological society is unsustainable. The high metal consumption pushes the mining and production of metals to levels that should be counterbalanced with novel engineering and technological methods that incorporate strategies of circular metal sustainability.
Dr. Žiga Štancar, a former colleague at the Jožef Stefan Institute’s Reactor physics department, contributed to the first direct experimental observation of thermonuclear fusion plasma self-heating by alpha ions in deuterium-tritium (DT) plasma, which is an important milestone on the pathway to demonstrative fusion reactors. The experiment, summarized in Physical Review Letters, was carried out at the largest magnetic confinement fusion device, the Joint European Torus (JET) tokamak. Led by dr. Vasily Kiptily of UKAEA, the researchers ran experiments with a DT and a comparable pure deuterium (D) plasma, externally heated with neutral beam injection, which resulted in high plasma temperature and fusion rate. Comparing the properties of the two plasmas immediately after the heating had been switched off revealed that the temperature of plasma electrons decreased in the D plasma, whereas it kept increasing for an additional 100 milliseconds in the DT plasma. This rise in electron temperature without external heating was ascribed to the collisional transfer of energy by the fusion-born fast alpha particles, which was corroborated by plasma simulations.
The severity of the SARS-CoV-2 pandemic and the recurring (re)emergence of viruses prompted the development of new therapeutic approaches that target viral and host factors crucial for viral infection. Colleagues Ana Mitrović and Janko Kos from Department of Biotehnology in collaboration with colleges from Faculty of Pharmacy, University of Ljubljana, and ICGEB in Trieste published the paper in journal Antiviral Research (IF = 10.103) entitled Cathepsin inhibitors nitroxoline and its derivatives inhibit SARS-CoV-2 infection. In paper the authors demonstrated that selective cathepsin B inhibitors, such as the antimicrobial agent nitroxoline and its derivatives, impair SARS-CoV-2 infection in vitro. Next, they observed antiviral activity observed at early stage of virus entry was cell-type dependent and correlated well with the intracellular content and enzymatic function of cathepsins B or L. Taken together, results from this study highlight the important role of host cysteine cathepsin B in SARS-CoV-2 virus entry and show that cathepsin-specific inhibitors, such as nitroxoline and its derivatives, could be used to treat COVID-19.
The members of several departments from Jožef Stefan Institute participate in the SiQUID (Slovenian Quantum Communication Infrastructure Demonstration) project for establishing quantum key distribution links between several state nodes in Slovenia and a testbed quantum network between research institutions in Ljubljana for advanced quantum communication protocols. Training key personnel, young researchers and engineers in the field of quantum technology is an important goal of SiQUID project. One of the activities in the project is also to test advanced quantum communication protocols and prepare the ground for a future full-scale quantum communication network. We are in close contact with QCI initiatives in all four neighbouring countries to facilitate harmonisation of national efforts and enable future cross-border interconnections and implementation of the EuroQCI space segment. Partners in the project: Faculty of Mathematics and Physics University of Ljubljana (coordinator), Jozef Stefan Institute, Beyond semiconductor d.o.o., Government Information Security Office and Government Office for the Protection of Classified Information.
At the Industrial Forum IRT 2023, the company MAHLE Electric Drives Slovenija d.o.o. and Jožef Stefan Institute received the TARAS award for successful cooperation between industry and academia. The subject of cooperation was the design of an electric motor for steering systems in vehicles. The goal was to determine its geometry and material properties such that the technical requirements are met and the cost minimized. We arrived at the solution through an innovative simulation-optimization process that includes the statistical evaluation of solutions considering deviations in the manufacture of the engine. The result is an advanced cost-effective engine that substantially improves the company's competitiveness on the market. The cooperation was initiated by the Center for Technology Transfer and Innovation in 2022, and the project was carried out by the Intelligent Systems Department (Bogdan Filipič, Tea Tušar, Aljoša Vodopija and Jordan Cork) and the Computer Systems Department (Peter Korošec).
The members of the Department of Complex Matter at the Jožef Stefan Institute and Faculty of Mathematics and Physics at University of Ljubljana Nerea Sebastián, Matija Lovšin, Natan Osterman, Irena Drevenšek Olenik in Alenka Mertelj, together with researchers from Ghent University (Belgium), University of Leeds (UK), and South China University of Technology (China) have recently published an article in Nature Communication with the title Polarization patterning in ferroelectric nematic liquids via flexoelectric coupling. The recently discovered ferroelectric nematic liquids incorporate to the functional combination of fluidity, processability and anisotropic optical properties of nematic liquids, an astonishing range of physical properties derived from the phase polarity. In this paper, it is shown that photopatterning of the alignment layer can be used to structure polarization patterns. These new capabilities of polarization patterning open a promising new route for the design of ferroelectric nematic based photonic structures and their exploitation.
The Springer publishing house has published a book by associates of the Department of communications systems Arsim Kelmendi, Aleš Švigelj, Tomaž Javornik, and Andrej Hrovat entitled Site Diversity in Satellite Communications: Modelling Using Copula Functions. The book is part of the Springer Briefs series. The book describes multi-site diversity modelling of induced rain attenuation statistics for satellite communication systems using copula functions. It collects all the relevant state-of-the- art findings, provides the missing pieces, and rounds them up in a way that the reader is given a complete picture of the important modelling factors and how to address them. Data post-processing methodology for statistical analysis based on our Earth-satellite propagation experiments are described. Four new models based on Copula functions for predicting diversity at multiple sites are presented with detailed comparative tests and error performance. The results presented in this book are intended to help improve system design and further research into modelling the next generation satellite links at higher frequencies.
Members of the Departments Computer Systems and Artificial Intelligence of Jožef Stefan Institute participate in the Horizon Europe project CONDUCTOR (Fleet and traffic management systems for conducting future cooperative mobility), where JSI develops advanced algorithms and performs technical coordination. As part of the three-year project, advanced traffic and fleet management will be designed, integrated and demonstrated, to allow for efficient and optimal transportation of passengers and goods. Modern algorithms of dynamic balancing and priority-based management of vehicles will be implemented. The project will develop a new generation of models and tools enabled by artificial intelligence and data fusion. Upgraded existing technologies will place autonomous vehicles in the cities of the future, with higher safety and flexible, responsive and centralized mobility control. This will lead to smoother traffic flow, less pollution and a higher quality of life. The resulting open platform will be validated in three use cases in different parts of Europe.
The journal Quantum Machine Intelligence has published an article entitled Boosting the Performance of Quantum Annealers using Machine Learning, authored by researchers from the Department of Knowledge Technologies, the Department of Complex Matter, the Jožef Stefan International Postgraduate School, the Nanocentre and the Faculty of Mathematics and Physics of the University of Ljubljana. The paper is co-authored by researchers Jure Brence, prof. dr. Dragan Mihailović, prof. dr. Viktor V. Kabanov, prof. dr. Ljupčo Todorovski in prof. dr. Sašo Džeroski, under the supervision of Dr. Jaka Vodeb, have managed to minimise the noise in quantum annealers using machine learning methods and thus improve their performance. Quantum annealers are a completely new type of computers that exploit the quantum dynamics of microscopic quantum bits to efficiently solve optimisation problems. They have succeeded in removing the influence of noise to such an extent that they have improved the performance of quantum annealers by three orders of magnitude, opening the way to solving more complex problems.
Researchers from the Department of Knowledge Technologies (E8) and the Computer Systems Department (E7) at JSI recently published a paper entitled OPTION: Optimization algorithm benchmarking ontology in the top-tier journal in Computer Science (IEEE Transactions on Evolutionary Computation, JCR IF = 16.4). The work presented is a collaboration with external partners from Sorbonne University, France, and Leiden University, the Netherlands. The focus of the paper is on the development of an ontology that enables semantic annotation of the core entities involved in the process of benchmarking optimization algorithms (based on evolutionary computation), which allows for a systematic way of sharing and reusing huge amounts of benchmarking data. The development of the OPTION ontology is a step forward in improving the reusability and interoperability of benchmarking data in the domain of optimization. It follows the principles of and contributes to the practice of Open Science.
The researchers from Department F6 have achieved an ultrafast differentiation by genomic GC content of the bacterial DNA at a molecular level using surface-enhanced Raman spectroscopy (SERS) and fine-tuned plasmonic gold nanocrystals. Their atmospheric-pressure plasma-designed truncated plasmonic particulates revealed truly exceptional optical response within nanometric gaps between gold dimers/chains, from where the molecular fingerprints of bacterial DNA fragments gained the strongest Raman signal enhancement. It allowed not only to collect vibrational data from different DNA samples but also, for the first time, to distinguish reliably between bacterial species due to intrinsically different compositions of nucleobases adenine, guanine, cytosine, and thymine within the biological macromolecule. The realized approach was successfully validated by cutting-edge third-generation sequencing nanopore technology and published in NanoLetters.
Turbulent flows in active nematic liquid crystals lead to spontaneous topological defect creation. Researchers Maruša Mur, Žiga Kos, Miha Ravnik and Igor Muševič from the Department of Condensed Matter Physics at the Jožef Stefan Institute and Faculty of Mathematics and Physics at the University of Ljubljana have published a paper in Nature Communications, titled Continuous generation of topological defects in a passively driven nematic liquid crystal, where they study a similar behavior in a passively driven system. Here, the flow is driven by a concentration gradient of small organic molecules added into a thin film of a nematic liquid crystal. Counter-rotating vortex rolls are generated in the film. Above a velocity threshold the flow transitions from a laminar into a turbulent regime, where topological defects start forming continuously. In the paper authors support their experimental findings by numerical simulations. The work describes one of the few mechanisms of topological defect creation in soft matter.
After his unanimous election last February, Prof. Dr. Jean-Marie Dubois, a member of the Department for Nanostructured Materials and honorary member of Jožef Stefan Institute, became a full member of the Académie Catholique de France on Oct 27th, 2022. This academy, created in 2018 in Paris, has several sections, among which one section assembles basic sciences, technologies and medicine. Prof. Dr. Jean-Marie Dubois, founder and first director of the Institute Jean Lamour, CNRS, world-renowned scientist, honorary doctor of several world universities, and a member of a few academies will share his knowledge of metallurgy and materials science and contribute to the discussions and debates that the academy promotes to cope with the current rapid changes of our society. His mentors, Prof. Dr Gilberte Chambeau and Prof. Dr Christian Amatore, were respectively head of the Chemistry Institute of CNRS and head of the Chemistry Department of Ecole Normale Supérieure in Paris.
Asst. prof. dr. Tome Eftimov and Prof. dr. Peter Korošec from the Computer Systems Department have published a Springer book entitled Deep Statistical Comparison for Meta-heuristic Stochastic Optimization Algorithms. The book is focused on robust statistical methods for benchmarking single- and multi-objective optimization meta-heuristics. Robust statistical methods are crucial for fair benchmarking and to increase the reproducibility and replicability of experiments. The work presented in the book was supported by the postdoc project “Mr-BEC: Modern approaches for benchmarking in evolutionary computation" led by Asst. prof. dr. Tome Eftimov, and the European Union's Horizon 2020 research and innovation program under grant agreement No. 692286 led by Prof. dr. Peter Korošec. The book provides approaches to trustworthy benchmarking that can easily be transferred to other research domains. The book is organized for researchers interested in basic and recent advances ins statistical analysis.
On Monday, September 19, 2022, the founding meeting of Council of Early Career Researchers of the "Jožef Stefan" Institute (SZK) was held in the large lecture hall of the JSI. At the meeting, which was also attended by the Director of the Institute, Prof. Boštjan Zalar, the candidates for membership in the Council introduced themselves. After an interesting discussion about the challenges faced by researchers at this stage of their career, the elections of the members of the SZK were held. The following members were elected and appointed to the Council: Asst. Prof. Tome Eftimov and Asst. Prof. Tadej Petrič in the field of electronics, information technology, energy; Asst. Prof. Matjaž Humar, Dr. Zala Lenarčič and Dr. Nerea Sebastian in the field of physics and nuclear engineering; Asst. Prof. Slavko Kralj and Asst. Prof. Matic Lozinšek in the field of chemistry, biochemistry, materials and environment and independent centers. The first meeting of the SZK will be organized shortly and you are cordially invited to attend.
The researchers of the department K5, Asst. Prof. Mojca Otoničar, Asst. Prof. Mirela Dragomir and Prof. Tadej Rojac, have published a feature article in the Journal of the American Ceramic Society (JACerS) titled Dynamics of domain walls in ferroelectrics and relaxors. The article presents the most important advances in the field of piezoelectric ceramics, focusing on the diverse and complex contributions of domain walls to the macroscopic functional properties of polycrystalline ceramics. Using nonlinear piezoelectric measurements supported by multiscale structural analysis, the authors show how local electrical conductivity in BiFeO3 and the structural disorder inherent to PMN-PT affect DW dynamics and lead to new macroscopic effects. This feature article provides evidence for analytical approaches to identify the key microscopic mechanisms that contribute to the macroscopic functional properties of ferroelectric and related materials. The authors also designed the cover of this issue of JACerS.
Prof. dr. Aleksander Rečnik received prestigious »Pannonia Award« following his 20-year collaboration with the Department of Geology and Environment, Faculty of Engineering at Pannonian University, and support of Hungarian doctoral students in electron microscopy of interfaces in their studies of phase transformations in materials. Joint research involved in–situ TEM experiments to study solid state reactions. In January 2022, a fundamental NKFIH–ARRS research project on aragonite twinning was approved for funding, where Hungarian and Slovenian researchers jointly tackle the problems related to the formation of aragonite under atmospheric conditions, which is one of the fundamental issues in mineralogy. The recognition to our colleague was awarded by the Academic Senate of the University of Pannonia and honors outstanding personalities with long–standing collaboration that substantially contributed to the development of new research areas at their university. Congratulations!
Researchers Saša Prelovšek Komelj from the Department of Theoretical Physics and M. Padmanath from Mainz find evidence for the longest-lived exotic state composed of quarks. Their article in Physical Review Letters establishes this state with an ab-initio study based on the fundamental theory for the first time. The state consists of two charm quarks together with antiquarks u and d, and was experimentally discovered at CERN by the LHCb collaboration in July 2021 - Nature Physics. It contains more than three quarks and therefore represents an exotic hadron. Conventional hadrons, for example, proton and neutron, are composed of up to three quarks. Investigations of exotic hadrons reveal whether the mechanisms responsible for their existence are analogous to those that bind protons and neutrons to nuclei, which are in turn responsible for the energy released in nuclear fusion and fission.
Prof. Barbara Malič, Head of the Electronic Ceramics Department is the recipient of the IEEE Ferroelectrics Recognition Award for the year 2022. The award is given by the Ferroelectrics Committee of the Ultrasonics, Ferroelectrics and Frequency Control Society (UFFC-S) for meritorious achievement in the field of Ferroelectricity or related sciences. Prof. Malič received the award for her outstanding contributions to the elucidation of the relationships between chemical and physical properties in ferroelectric ceramics at the 2022 ISAF-PFM-ECAPD joint conference International Symposium on Applications of Ferroelectrics – Piezoresponse Force Microscopy International Workshop-European Conference on Applications of Polar Dielctrics which took place from June 27 to July 1, 2022, in Tours, France. The award is not only a recognition of the research of the recipient but also the confirmation of the excellence of ferroelectrics research within the Electronic Ceramics Department placing it among the best research groups in the field.
Andrej Zorko from the Solid State Physics Department is the recipient of the 2022 Science Impact Award for his work on quantum spin liquids. This award is given annually by the Science and Technology Facilities Council from the United Kingdom to celebrate the scientific impact of the research conducted at the ISIS, Rutherford Appleton Laboratory large-scale user facility in the last five years. This is a world-leading research centre than supports more than 2000 researchers applying neutron scattering and muon spectroscopy to various fields of natural sciences. Andrej Zorko led an international research group and was awarded for their discovery of the first realization of a quantum spin liquid on a triangular spin lattice with dominant Ising antiferromagnetic exchange interactions, which has recently been published in Nature Materials. These results revealed that the family of rare-earth heptatantalates represents a novel framework for quantum spin liquids.
On May 31, 2022, Prof. Ingrid Milošev, Head of Department fof Physical and Organic Chemistry at Jožef Stefan Institute presented a webinar within the second season of the CorroZoom, series organized by Prof. G. S. Frankel at The Ohio State University, Columbus, USA. This year, six top scientists from all over the world gave lectures on different corrosion-related topics, where Prof. Milošev had the honor of concluding the second season. Lecture entitled "Cerium conversion coatings on aluminium alloys" covered some fundamental considerations of the chemistry of Ce salts and general mechanisms of coatings formation, followed by examples from her group's research work on this type of coatings. The lecture, attended by around 300 participants worldwide, was followed by a broad discussion on the topic. Presenting at the CorroZoom webinar is a great acknowledgment and compliment to Prof. Milošev's over three decades-long research work dedicated to corrosion protection, including conversion coatings.
Associate of the Department of Condensed Mater Physics of the Jožef Stefan Institute Professor Slobodan Žumer and his Marie Curie postdoctoral researcher Guilhem Poy at the Faculty of Mathematics and Physics, University of Ljubljana, in collaboration with the experimental soft mater physics group of Professor Ivan Smalyukh at University of Colorado Boulder, made an important contribution to the interpretation and successful realization of a controlled opto-mechanical interaction of optical and topological solitons in frustrated chiral nematic liquid crystals. Finding of an unusual traction effect of particular optical solitons in such media allows light-induced periodic arrangement of topological solitons that in addition to the scientific aspect, has a potentially important relevance for use in the soft matter photonics. The authors recently published the results of this research in the article Interaction and co-assembly of optical and topological solitons in the renowned journal Nature Photonics.
The Department of Environmental Sciences (O2) has recently obtained a new Horizon EU EU project, FishEUTrust: European integration of new technologies and socio-economic solutions for increasing consumer trust and engagement in seafood products coordinated by Prof. Nives Ogrinc. The four-year project, worth five million euros, involves 21 partners from 14 countries including 11 SMEs and two international organizations, i.e., EUROFISH and the EU Aquaculture Society. The project aims to establish a comprehensive approach to ensure a sustainable fish and seafood supply chain by developing new technological solutions for greater transparency and traceability, including metagenomic approaches combined with stable isotopes of light elements, sensor technologies and AI-based analysis to ensure safety and freshness as well as digitization. The project will also address consumer behavior and promote sustainable aquaculture and the blue economy. The Department of Computer Systems (E7) will also participate in the project with ICT and data science activities led by Prof. Barbara Koroušić Seljak.
With the publication of the e-manual for digital intellectual property management in companies, the SRIP ToP Factory of the Future Center at the Jožef Stefan Institute completed the Go-DIP project - Digital Intellectual Property Management in Digital Enterprise Digitization Processes. The project addresses the current challenges of the European Community in the field of access, use and re-use of data, ethical use and trust in data in the field of artificial intelligence and open data. The Go-DIP project monitored various aspects of digital intellectual property management practices in companies in three areas: digital data sharing and digital data-based innovation, software intellectual property management and data management, and data ownership and exploitation of data intellectual property. The manual is free and available for download. The Go-Dip project was implemented within the Horizon Innosup 2018-2020 program. The total value of the project was EUR 50,000. The participating partners in the project were Hub Inovazione Trentino from Italy and Innosquare from Frieburg in Switzerland.
As a part of our ongoing research with twisted light (light that carries orbital angular momentum) conducted in collaboration with researchers from the University of Nova Gorica and the Institute of Physics at the University of Halle, Špela Krušič, Andrej Mihelič and Matjaž Žitnik from the F2 department published an article, in the Physical Review Letters showing that light can magnetize matter on a nanometer scale. With a short and strongly focused XUV light pulse from the FERMI free electron laser, a large portion of helium atoms in the gas target was transferred from the ground state to a singly excited state, and from there to a ‘rotating’ Rydberg state with a simultaneous pulse of twisted IR light. The analysis of dichroism in the photoelectron signal showed that the atomic current loops of the rotating Rydberg wave packets generate a magnetic field that is localized along the axis of the twisted light beam and is stable on the time scale determined by the lifetime of the Rydberg state. The figure from the article is featured on the cover of the latest issue of the PRL, and the article is highlighted in Synopsis in Physics.
Researchers Assist. Prof. Sašo Gyergyek and Prof. Darko Makovec from the Department for Materials Synthesis, in collaboration with researchers from the Department of Catalysis and Reaction Engineering of the National Institute of Chemistry, published a paper in Green Chemistry entitled Electro-hydrogenation of biomass-derived levulinic acid to γ-valerolactone via the magnetic heating of a Ru nanocatalyst. In the paper they demonstrate application of heating of magnetic nanoparticles imbedded within a Ru-based composite catalyst when exposed to alternating magnetic field to drive chemical reaction. The in-depth analysis and modelling of surface processes showed that the surface of the catalyst reaches a higher temperature than bulk of the medium, resulting in an increased rate of conversion and thus increasing the yield of γ-valerolactone under mild conditions. The research demonstrates the high potential of magnetic heating for heterogeneous reaction systems with thermally labile reactant, such as biomass components.
Researchers Aljaž Kavčič, dr. Maja Garvas, Matevž Marinčič and doc. dr. Matjaž Humar from the F5 department and dr. Boris Majaron from the F7 department of the Jožef Stefan Institute have, in collaboration with researchers from Graz University, published a paper in Nature Communications entitled Deep tissue localization and sensing using optical microcavity probes. In the paper they presented a new method for imaging through scattering tissues, based on localization of whispering gallery mode microresonators with spectrally narrow emission that enables a decomposition of diffuse signal into contributions from individual microresonators. The developed method combines the ability of precise localization on cellular level with possibility of sensing various parameters such as temperature, pH and refractive index, which makes it a versatile and promising tool in the field of deep-tissue imaging. First author of the paper Aljaž Kavčič presented the results of this work in his master’s thesis, for which he was awarded »Prešernova nagrada« of University of Ljubljana.
The second CrossNano, Crossborder Workshop in Nanoscience and Nanotechnology, took place on 22–24. 2. 2022. The workshop was organized by the University of Trieste, Jožef Stefan International Postgraduate School and Jožef Stefan Institute. The workshop's aims to stronger crossborder cooperation between the participating institutions and our future scientists. 53 students of nanoscience and nanotechnology from the PhD School in Nanotechnology from University of Trieste, Jožef Stefan International Postgraduate School, University of Ljubljana, and University of Maribor participated this year. Giulia Della Pelle (Department of Nanostructured Materials, JSI) and Valeria Chesnyak (University of Trieste) received the "Fernando Tommasini" award for the most comprehensive presentation. Spase Stojanov (Department of Biotechnology, JSI) and Veronika Kost (University of Trieste) received the "Alessandro de Vita" award for the highest level of multidisciplinary and scientific curiosity. Congratulations to all the winners and their mentors.
Researchers from the EUROfusion consortium, including JSI researchers, used the Joint European Torus (JET) device to release a record 59 MJ of sustained fusion energy. The breakthrough achievement on JET, the world’s most powerful operational fusion facility based in Oxford, almost tripled the previous fusion energy record. These experiments are a major boost for Iter, the larger and more advanced version of JET. Iter is an experimental fusion reactor under construction in southern France. The EUROfusion consortium, co-funded by the European Commission, integrates 4800 researchers from 30 research organisations. 8 departments and more than 40 researchers from Jožef Stefan Institute are involved in EUROfusion consortium. Dr. Boštjan Končar, R4, SFA: »The achievement is also the result of many years of hard work by Slovenian researchers, especially in the field of neutron transport calculations, diagnostics, analyses and preparation of fusion experiments.”
Researchers Jaka Pišljar, Miha Škarabot, Andriy Nych, Matevž Marinčič, Miha Ravnik and Igor Muševič from the F5 department and Alenka Mertelj and Andrej Petelin from the F7 department of the Jožef Stefan Institute have in collaboration with researchers from University of Kolkata and Assam in India published a new research paper entitled BPIII: Topological Fluid of Skyrmions in the Physical Review X journal. In their work, the authors use several experimental techniques aided by numerical simulations to elucidate the intriguing and so far not definitively explained structure of the blue phase III (BPIII) found in highly chiral liquid crystals. They show that in bulk, the BPIII is a highly dynamic disordered tangle of skyrmion filaments, which in thin layers disentangle into a 2D lattice of half-skyrmions. These filaments are like long ropes with a cross-section of a vortex whirling from the center to the periphery. In their structure, they are akin to magnetic skyrmions, which have been widely researched in the last decades for applications in information storage.
In the News and Views section of Nature, Denis Golež [Department of Theoretical Physics and Department of Complex Matter, Jožef Stefan Institute, and the University of Ljubljana] and Zhiyuan Sun [Harvard University] published an article A compact device sustains a fluid of bosons. Authors describe the discovery of an exotic fluid of particles in a device designed from thin layers of semiconductors. The fluid is composed of bosonic particles, bound pairs of electrons and holes in a semiconductor, called excitons. Although the experiment could not prove quantum coherence and superfluid unambiguously, the work represents a significant step toward stabilizing Bose-Einstein condensate at high temperatures and equilibrium conditions. Authors present their vision of the field based on precise manipulation of materials on the nanoscale to reach coherent quantum states. They finish with propositions for various useful devices which could emerge from such an effort, including excitonic transistors, memory elements and even quantum simulators.
Doc. dr. Matjaž Humar from the Department of Condensed Matter Physics at Jožef Stefan Institute, and researchers from UK, USA and Japan have published an article titled Whispering-gallery-mode sensors for biological and physical sensing in Nature Reviews Methods Primers. In the paper the authors introduce whispering-gallery-mode microcavities in different geometries, such as microspheres, microtoroids, microcapillaries and microrings. Whispering-gallery-mode microcavities are miniature micro-interferometers that use the multiple-cavity passes of light for very sensitive measurements at the microscale and nanoscale, including single-molecule and ion measurements. The authors describe sensing mechanisms, including mode splitting and resonance shift, and optomechanical and optoplasmonic signal transductions. Applications and experimental results cover in-vivo and single-molecule sensing, gyroscopes and microcavity quantum electrodynamics.
Neelakandan M Santhosh and colleagues from the Department for Gaseous Electronics have recently published a scientific article Advancing Li-ion storage performance with hybrid vertical carbon/Ni3S2-based electrodes in collaboration with researchers from Kyung Hee University, South Korea. In this article, the authors demonstrate a fast and feasible method to develop hybrid nanostructure-based electrode materials to advance the Li-ion storage capabilities of batteries. Targeting to develop energy storage materials for next-generation devices, they successfully fabricated a hybrid electrode material comprised of carbon nanotube and nickel sulfide. Based on the electrochemical energy storage performance, the reported electrode material outperforms most of the similar electrode materials by achieving ultra-high specific capacity and excellent long term stability. Developing ultra-high performing energy materials is critical as the demand for alternative energy sources and consumer needs increases. Therefore, the findings of this article could provide a path towards designing next-generation battery materials at a low cost.
In an extensive study, Jeffrey C. Everts and Miha Ravnik from the Faculty of Mathematics and Physics at University of Ljubljana and the Department F5 of Jožef Stefan Institute examined the details of the coupling of ions and singular topological defects in complex nematic fluids (Phys. Rev. X 2021). The authors showed that topological defects in nematic electrolytes could perform as areas for local separation of electric charge, forming electrically charged cores of defect and in selected geometries also electrical multi-layers. These charge distribution are generalizations of electrical double layers known in isotropic electrolytes. In particular, they show that ions couple very efficiently with the defect cores through the mechanism of ionic solubility, and with the surrounding orientation field deformations through the mechanism of flexoelectricity. The work is a significant contribution towards understanding the electrostatic mechanisms in complex soft matter.
The colleagues from Department for Gaseous Electronics of JOžef Stefan Institute and their partners within the H2020 FET-Open project “Pegasus” developed and demonstrated a novel and green approach in process engineering of graphene nanostructures used for green systems in energy storage. The researchers report one of the fastest methods for synthesizing nitrogen-doped graphene and incorporating metal oxide /sulfide nanoparticles into graphene layers simultaneously using a microwave plasma system. The authors revealed that produced graphene hybrids have higher quality and low production costs than commercially available graphene. The production method does not involve any complex chemical treatments and is an environmentally benign process. The reported plasma-driven environmental-benign approach could open many opportunities for different applications, especially for next-generation energy materials. The scientific article N-Graphene-Metal-oxide(sulfide) Hybrid Nanostructures: Single-Step Plasma-Enabled Approach for Energy Storage Applications was published in Chemical Engineering Journal, whereas the process was protected.
The physical behavior of anisotropic charged colloidal particles in nematic solvents is determined by their dielectric anisotropy. Together with the experimental group of Professor Ivan Smalyukh at University of Colorado Boulder the authors Jeffrey C. Everts and Miha Ravnik from the Faculty of Mathematics and Physics at University of Ljubljana and the Department F5 of Jozef Stefan Institute demonstrated anisotropic electrostatic screening for charged colloidal particles in nematic electrolytes. The electrostatic potential and pair interactions decay with an anisotropic Debye screening length, contrasting constant screening length for isotropic electrolytes. Charged dumpling-shaped near-spherical colloidal particles in nematic media are used as model systems, demonstrating competing anisotropic elastic and electrostatic effective pair interactions for colloidal surface charges tunable from neutral to high, yielding particle-separated metastable states (Science Advances 2021, DOI: 10.1126/sciadv.abd0662). The work was published in Science Advances and contributes to the understanding of electrostatic screening in nematic media.
The colleagues from Department for Gaseous Electronics of Jožef Stefan Institute have recently published their scientific achievements titled Label-Free Mycotoxin Raman Identification by High-Performing Plasmonic Vertical Carbon Nanostructures in top-ranked journal SMALL focused on highly important results applied at the nano- and microscale research. Targeting to improve sensing performance of vibrational-related detectors, they successfully designed a novel nanoplasmonic sensor possessing superior optical response, flexibility and robustness. Based on gold-decorated carbon nanotubes structures grown by plasma-assisted synthesis on top of a catalytic Ni foil, the reported sensor was able to provide a ppb-level Raman detection of highly hazardous mycotoxins. These secondary produced metabolites are known for their cancerogenic effect and world-wide abundance, especially in various cereals. The article reveals that mycotoxin type can be not only precisely indicated at ultralow quantities, but also accurately recognized by spectroscopic features, allowing to advance significantly the investigation of health-harmful chemical toxins.
A Nd–Fe–B permanent magnet, indispensable when it comes to green technologies for low carbon society, typically contains 28–35 wt% rare-earth elements (REEs, e.g., Pr, Nd, Tb, and Dy). This means that end-of-life (EoL) magnets are an important secondary resource for REEs that EU considers as the most critical. Dr. Xuan Xu, Prof. Sašo Šturm and Prof. Kristina Žužek Rožman (Department for Nanostructured Materials) were awarded with a silver medal for the innovation on the International exhibition ARCA in Zagreb Croatia. The innovation »Enviromentally friendly and energy effecient method for recovery of rare earth elements« contributes to a more sustainable and greener EU future with regards to recycling of critical raw materials i.e the rare earths from permanent magnets. The developed method (in the frame of MSCA DEMETER project) is based on electrochemical aspects and is environmentally friendly and energy efficient. The innovation was presented in collaboration with the Technology transfer office from Jožef Stefan Institute.
Dr. Martin Klanjšek from the Condensed Matter Physics Department published a News & Views article entitled Singlets singled out in Nature Physics upon invitation by the editor. In this article, the author presents his view of the achievements of the article Emergence of spin singlets with inhomogeneous gaps in the kagome lattice Heisenberg antiferromagnets Zn-barlowite and herbertsmithite published in the same journal by the research group of prof. Imai from the McMaster University in Canada. They report on the gradual formation of spin singlets in two quantum magnets with kagome lattice, which is an important step in the resolution of the ground state of this archetypal magnet. News & Views section contains short articles summarizing recently published high-impact research in a way accessible to the broader public. The authors of the News & Views articles are selected by the editor among those reviewers of the corresponding research articles that left the best impression during the review process.
The members of the Department of Complex Matter at the Jožef Stefan Institute doc. dr. Alenka Mertelj and dr. Nerea Sebastián, together with Richard J. Mandle for the University of Leeds and Josu Martinez-Perdiguero from the University of the Basque Country have recently published an article in Nature Communications with the title On the molecular origins of the splay nematic phase. Polar nematic phases have been long-time predicted, but have only been experimentally realized recently. In this paper, the authors compare, both experimentally and by means of molecular dynamic simulations, two materials with similar chemical structure and demonstrate that a subtle molecular change enables denser packing when they exhibit polar order. Such reduction of the excluded volume lies in the origin of the polar nematic phase. This contribution shows how MD simulations can be used for molecular design, by predicting and identifying candidate materials for the polar or its precursor nematic phases.
Dr Ingrid Milošev, Head of Department of Physical and Organic Chemistry at Jožef Stefan Institute, has been named to the CORROSION journal Editorial Board as an Associate Editor. CORROSION was started in 1945 by the Association of Materials Protection and Performance (AMPP, former NACE). AMPP is a global community of professionals dedicated to materials protection through the advancement of corrosion control and protective coatings with more than 40,000 members in 130 countries CORROSION journal, led by Technical Editor in Chief Dr John Scully, provides a permanent record of progress in the science and technology of corrosion prevention and control, featuring peer-reviewed technical articles from the world’s top researchers. CORROSION journal welcomed new Associate Editor by Editorial article and podcast interview. The majority of 16 Associate Editors are from the USA, three members are from Europe. Dr. Ingrid Milošev has been named to the Board as the second female member.
Researchers from Jožef Stefan Institute Melita Sluban, Polona Umek (F5) and Jernej Iskra (K3) have in collaboration with the colleagues from the universities of Ljubljana and Bucharest successfully catalysed aldol condensation with protonated titanate nanotubes. This is a 'green' alternative to the present reaction performance at the industrial level where stoichiometric amounts of homogeneous catalyst are used and the catalyst cannot be recycled. With protonated titanate nanotubes, catalytic amounts of the material sufficed for the reaction progress, the catalyst was reused for several times and was efficient even in a large-scale experiment. The work entitled Protonated titanate nanotubes as solid acid catalyst for aldol condensation was published in Journal of Catalysis.
The Physical Review Letters journal has recently published a paper entitled Low-Temperature Global Symmetry Reduction in the Kagome Antiferromagnet Herbertsmithite, written by Andrej Zorko and Matjaž Gomilšek from the Solid State Physics Department, Jožef Stefan Institute. In collaboration with research groups from Croatia, USA, and France, they have observed for the first time a reduction of symmetry in herbertsmithite, a paradigm of quantum spin liquids on the kagome lattice with a theoretically predicted spin-liquid ground state. The symmetry reduction could finally provide a key clue about the nature of the ground state in this mineral. After more than a decade of intense research, this discovery provides a novel viewpoint on the enigmatic spin-liquid ground state of the kagome lattice.
Researchers from Jozef Stefan Institute and National Institute of Chemistry, in collaboration with colleagues from Switzerland and Japan, were the first to identify accumulation of charged defects at domain walls in ferroelectric BiFeO3. This finding explains the p-type hopping conduction at the domain walls in BiFeO3 and thus represents the missing piece for explaining the intriguing electrical properties of domain walls in ferroelectrics. The study was published in Nature Materials with a 2015 impact factor of 38.89, which currently makes it one of the highest-impact scientific journals. (T. Rojac, A. Bencan, G. Drazic, N. Sakamoto, H. Ursic, B. Jancar, G. Tavcar, M. Makarovic, J. Walker, B. Malic in D. Damjanovic; Domain wall conduction in ferroelectric BiFeO3 controlled by accumulation of charged defects. The entire study was conceived and experimentally implemented at the two Slovenian research institutions.
The paper entitled Network traffic modeling for load prediction: a user-centric approach published in IEEE Network, authored by two researchers from the Department of communications systems prof. dr. Aleš Švigelj and dr. Kemal Alič and dr. Radovan Sernec from Telekoma Slovenije, was selected for the Best Paper Award of the IEEE ComSoc Technical Committee on Communications Systems Integration and Modeling. The award will be presented during the prestigious IEEE Globecom 2016 conference held in December in Washington D.C., USA. The paper addresses an innovative user-centric approach to network traffic modelling that was validated and used in the process of introducing, optimizing, and planning of new services at the Slovenian national telecom operator and service provider.
Matjaž Humar from Condensed Matter Physics department at Jožef Stefan Institute won 1st Place Poster Prize at prestigious Nobel Laureate Meeting 2016. The meeting has taken place in Lindau, Germany from 26. June to 1. July. There were 400 invited young scientists from 80 countries and 29 Nobel laureates attending the 66. Lindau Nobel Laureate Meeting. The attendees of the meeting are carefully selected by a committee giving priority to young scientists who are strongly committed to science and research. This year meeting was focused on physics. Matjaž presented a poster about lasers embedded into single live cells. His poster got the most votes given by the young scientists and Nobel laureates.
Researchers from the Department of Automation, Biocybernetics and Robotics at Jožef Stefan Institute in collaboration with the colleagues from Technical University Darmstadt in Germany have revealed mechanisms of how human central nervous system controls the motion of our body during physical interaction with the environment. They examined adaptation to systematic postural perturbations while the human subjects had to perform a series of goal oriented movements. By employing a novel probabilistic modeling approach, the researchers established a computational model that explained how our brain arbitrates between goal oriented movements and maintaining postural balance. The findings of the study were published by Nature Scientific reports.
On May 23 and 24, 2016 Prof. Kiyoshi Tanaka, a Vice-President of Shinshu University, Nagano, Japan, and Hernán Aguirre, an Associated Professor at Shinshu University, were visiting the Jožef Stefan Institute. The purpose of the visit was to start a scientific cooperation between the two institutions supported by the Slovenian Research Agency and Japan Society for the Promotion of Science. To this end, the two sides agreed on a memorandum that was signed by the Director of JSI Prof. Jadran Lenarčič on May 24. The joint research focuses on multi-criteria optimization for space exploration and infrastructure networks. At JSI it is conducted by the Computational Intelligence Group of the Department of Intelligent Systems led by Prof. Bogdan Filipič.
The journal Scientific Reports published on May 20, 2016 the article entitled "Points, skyrmions and torons in chiral nematic droplets", by Gregor Posnjak, Simon Čopar and Igor Muševič, members of the Solid State Department (F5) of JSI and Faculty of Mathematics and Physics, University of Ljubljana. They discovered a new method of reconstructing 3D orientational field of a liquid crystal, labelled with fluorescent molecules and imaged with a confocal optical microscope. Using this method they were able for the first time to determine unambigously the topological properties of a chiral liquid crystal, captured in a micro-droplet, as tiny as a hair. They could see singular point-like topological defects, separated by 3D topological objects, which are known in physics as skyrmions and torons.
On Monday, 16 May 2016 the group led by Prof. Dr. Dragan Mihailović from department of Complex Matter, Jozef Stefan Institute published an article entitled Fast electronic resistance switching involving hidden charge density wave states in Nature Communications. The article describes the way for electrical control of a new type of memory element with a record speed. Nowadays the speed of memory is the main constraint slowing down supercomputers, which everybody of us is using while surfing Google, Amazon, eBay, etc. Experimental work, in which the main contributors are dr. Igor Vaskivskyi, Ian Mihailović and Damjan Svetin, describes a record fast electrically driven memory element, in which the writing process occurs in just 40 picoseconds. The previous world record was held by an American group. The group of Jozef Stefan Institute improved their record by about 10 times.
Researchers from the Jožef Stefan Institute (Department for Materials Synthesis and Department for Complex Matter) and the University of Ljubljana, Darja Lisjak, Alenka Mertelj and Martin Čopič, in collaboration with researchers from the USA (University in Boulder, Lawrence Berkeley National Laboratory and Case Western Reserve University) have discovered that suspensions of magnetic nanoplatelets in butanol exhibit ferromagnetic ordering. Its zero-field magnetization produces distinctive magnetic self-interaction effects, including liquid-crystal textures of fluid block domains arranged in closed flux loops, and makes this phase highly sensitive, with it dramatically changing shape even in the Earth’s magnetic field. The discovery was published in Nature Communications.
Matjaž Humar from Jožef Stefan Institute, Condensed Matter Physics, who is currently a Marie Curie fellow at Harvard Medical School, has published in collaboration with researchers from Massachusetts General Hospital an article Bioabsorbable polymer optical waveguides for deep-tissue photomedicine in Nature Communications. The authors made a new class of optical waveguides for deep-tissue photomedicine made out of biocompatible and biodegradable polymer materials, which can be implanted into the body and are naturally degraded over time. The waveguides enable the use of a number of medical laser treatments and diagnostics deep into the body, which were till now only limited to the surface of the body due to limited penetration of light into the tissues. As an example of a possible application, laser wound closure is demonstrated, leading to faster healing and less scarring.
Julian Walker, Hana Uršič, Andreja Benčan, Barbara Malič and Tadej Rojac from the Electronic Ceramics Department (K-5), in collaboration with researchers from Denmark, Russia, Portugal and Australia, published their work ˝Dual strain mechanisms in a lead-free morphotropic phase boundary ferroelectric˝ in the January 2016 issue of Nature Scientific Reports (DOI: 10.1038/srep19630). The work focuses on (Bi,Sm)FeO3 compositions at the morphotropic phase boundary, where they identified a previously unreported electric-field-induced phase transition. The authors demonstrate the unique occurrence of dual strain mechanisms consisting of ferroelastic domain switching and a field-induced phase transition, which simultaneously contribute to the macroscopic strain behaviour of these lead-free ferroelectric materials.
N. Kostevšek, S. Šturm and K. Žužek Rožman from the Jožef Stefan Institute, Department for Nanostructured Materials, in collaboration with partners from Bologna, Trieste and Torino, have published in Chemical Communications an article entitled The one-step synthesis and surface functionalization of dumbbell-like gold–iron oxide nanoparticles: a chitosan-based nano-theranostic system. It was shown that the hybrid Au-Fe oxide nanoparticles, equipped with a biocompatible chitosan coating, are introducing an effective system for biomedical diagnostics and therapy. As prepared, nanoparticles exhibit photo-acoustic effect, which presents a new and non-invasive way of imaging. Moreover, their photo-thermal response can be used for an efficient and selective treatment of the targeted tissues.
Researchers from the Condensed Matter Physics and Complex Matter Physics departments of the Jožef Stefan Institute, in collaboration with partners from Belgium, France and Germany, have shown that the slow anion diffusion in anion-exchange reactions can be efficiently used to tune the disorder strength and the related electronic properties of nanoparticles. This was shown for the case of titanium oxy-nitride nanoribbons. By controlling the nitrogen content, which determines the chemical disorder through random O/N occupancy and ion vacancies, they effected the transition from “bad metal” to the superconducting state. This shows that with anion exchange, not only can the structural order be affected, but so can the physical and functional properties of these materials. The results were published in the journal ACS NANO.
The magnetic response of magnetic insulators is determined by the coupling between the magnetic moments, which is usually temperature independent. A theoretical work dating from the 1980s showed that the eventual temperature dependence originates from the thermal expansion of the lattice, while the contribution of the lattice vibrations could be considered negligible. In contrast, Martin Klanjšek and Denis Arčon from the Condensed Matter Physics department at the Jožef Stefan Institute, together with German colleagues who synthesized the sample, showed that the magnetic coupling in caesium superoxide is strongly temperature dependent, precisely as a result of the librations of the magnetic superoxide molecules. This first confirmation of the dynamic modulation of the magnetic coupling, a prototypical phenomenon relevant for a range of other molecular magnets, is described in the recently published article in Physical Review Letters.
Researchers at the Jožef Stefan Institute have succeeded in making a very important breakthrough - for the first time they were able to implant a laser into a single human cell. Furthermore, they have demonstrated that the fat cells in our body already contain lasers, which need only to be activated. In both cases the lasers are in the form of small solid spheres or lipid droplets. Deformation of the droplets enables accurate measurements of the forces inside the cells. The emission of each laser within a cell can also be used as a barcode with enough unique combinations to tag all the cells in the human body. This discovery was published in the Nature Photonics paper Intracellular microlasers. The authors are Dr Matjaž Humar from the Condensed Matter Physics department of the JSI, who is currently on a postdoc at Harvard Medical School, USA, and Seok-Hyun Yun - video.
On 12 June 2015, the journal Nature Communications published an article entitled “Spin-stripe phase in a frustrated zigzag spin-1/2 chain”, by Matej Pregelj, Andrej Zorko and Denis Arčon from the Condensed Matter Physics (F5) department at the Jožef Stefan Institute, in collaboration with partners from Switzerland, France and Japan. The results unveil the beta-TeVO4 compound as a model system of a frustrated spin chain. The main result is the discovery of a magnetic stripe structure on the nanoscale, which appears at the transition between the spiral and collinear magnetic orders. In contrast to known modulated electron systems, in beta-TeVO4 the stripes are stabilized in the absence of long-range interactions. The presented system thus allows a better understanding of the origin of the intriguing nanometre-sized modulation in other systems, e.g., high-temperature superconductors.
Researchers at the Jožef Stefan Institute have identified an unexpectedly general set of rules that determine which molecules can cause the immune system to become vulnerable to the autoimmune disorders lupus and psoriasis. Autoimmune diseases strike when the body attacks itself because it fails to distinguish between host tissue and disease-causing agents, or pathogens. When a healthy person is infected by a virus, viral DNA can activate the immune cells via a receptor called TLR9. The receptor triggers the cells to send signalling molecules called interferons to initiate a powerful defensive response. In people with lupus or psoriasis, these cells are activated by their own DNA, or self-DNA. A team of scientists has shown that the process of DNA-induced amplification of interferon production is more physical in nature than had been expected. An interplay of electrostatics and multivalent binding results in multivalent activation: only those complexes with a DNA interstrand spacing corresponding to the dimensions of the toll-like receptor binding sites trigger a strong immune response.
With an important contribution from Denis Arčon, Peter Jeglič and Anton Potočnik from the Solid State Physics Department, a new type of metallic state of matter has been discovered by an international team of researchers studying a superconductor made from C60 molecules. The team found this new metallic state after changing the distance between neighbouring C60 molecules by doping the parent Cs3C60 material with rubidium. The study revealed that the material has a remarkably rich combination of insulating, magnetic, metallic and superconducting phases – including the hitherto unknown state, which the researchers have dubbed a "Jahn–Teller metal". The article was recently published in Science Advances, a new research journal of AAAS (Science), and has been picked up by several news sources, including physicsworld.com.
On 15 May 2015, the Advanced Functional Materials journal published the article Controllable Broadband Absorption in the Mixed Phase of Metamagnets, written by Matej Pregelj, Andrej Zorko and Matjaž Gomilšek from the Condensed Matter Physics department at the Jožef Stafan Institute, in collaboration with partners from Switzerland, Germany and Moldova. The article reveals the ability of metamagnetic materials to absorb electromagnetic radiation across an extremely broad frequency range. The effect is controlled by an external magnetic field, which actuates a mixed ferro/antiferromagnetic phase, where the absorption in the Cu3Bi(SeO3)2O2Br system extends over at least nine orders of the frequency scale. Considering that artificial metamagnets (magnetic multilayers) allow for direct control over the required magnetic field, a novel way of tuning the material’s properties is imminent.
Asst. Prof. Tadej Rojac, Dr Hana Uršič, Asst. Prof. Andreja Benčan and Prof. Barbara Malič from the Electronic Ceramics Department, Jožef Stefan Institute, in collaboration with Prof. Dragan Damjanović, from the Swiss Federal Institute of Technology, published their recent results on Mobile Domain Walls as a Bridge between Nanoscale Conductivity and Macroscopic Electromechanical Response in Advanced Functional Materials. They showed that in polycrystalline BiFeO3 the local domain-wall conductivity within the grains results in an unexpectedly large effect on the macroscopic piezoelectric response. Their results bridge the local conductivity and the macroscopic piezoelectricity via domain-wall dynamics, revealing that the domain-wall conductivity must be considered when interpreting and controlling the macroscopic electro-mechanical properties of piezoelectric ceramics.
Caesium atoms have been trapped and cooled for the first time in the Laboratory for Cold Atoms at the Solid State Physics Department of the Jožef Stefan Institute in collaboration with the Theoretical Physics Department and Low and Medium Energy Physics Department. A view through the vacuum chamber viewport shows a fluorescing tiny pink cloud containing 50 million caesium atoms levitating at a few hundred microkelvin. In the next step, the atoms will be transferred to the dipole trap produced by high-power laser light and finally cooled down by evaporation to reach temperatures below 50 nanokelvin, where the Bose-Einstein condensation takes place. More information about the laser cooling and trapping methods is available at ultracool.ijs.si.
In a recently published article in Nature Physics prof. J. Bonča from the Department of Theoretical Physics, together with his former PhD students, dr. L. Vidmar and dr. D. Golež, and an experimental group from Italy, addressed one of the pivotal questions in the physics of high-temperature superconductors concerning the question of whether the low-energy dynamics of the charge carriers is mediated by bosons with a characteristic timescale. The answer to this question has remained elusive as electronic correlations are expected to greatly accelerate the electron–boson scattering processes, confining them to the very femtosecond timescale. The experimentally observed timescale is in agreement with numerical calculations on a model in which the relaxation of the photo-excited charges is achieved via inelastic scattering with short-range antiferromagnetic excitations.
Silver(II) compounds exhibit a broad range of peculiar physicochemical properties, which are described in the review "Chemistry of Silver(II): a Cornucopia of Peculiarities" written by Wojciech Grochala of the University of Warsaw and Zoran Mazej of the Jožef Stefan Institute. Their review paper has been published in the journal Philosophical Transactions A, published by the Royal Society (London). Phil. Trans. R. Soc. A is the oldest journal in the world that is dedicated only to science. The first issue appeared in March 1665, and so this year the journal is celebrating its 350th anniversary. Each issue is focused on a specific topic. The 13 March 2015 issue, in which the paper is published, has the title "The new chemistry of the elements" and is dedicated to the importance of the periodic table.
The PNAS journal, which is celebrating its 100th anniversary in 2015, has recently published a paper entitled Knot theory realizations in nematic colloids, by Simon Čopar, Uroš Tkalec, Igor Muševič and Slobodan Žumer from the Faculty of Mathematics and Physics in Ljubljana, the Faculty of Natural Sciences and Mathematics in Maribor, and the Solid State Physics Department of the Jožef Stefan Institute.
The authors report diverse applications of knot theory in nematic liquid-crystal colloids with knotted defect loops. The results demonstrate how the construction of graphs, topological surfaces and knot polynomials is showcased directly on experimental micrographs, thereby identifying the entangled structures without the need for numerical simulations. The paper illustrates how abstract mathematical concepts manifest elegantly as observable features in soft-matter physics.
Dr Marko Soderžnik, working on the FP7 project entitled “Replacement and Original Magnet Engineering Options (ROMEO)”, which is coordinated by prof. Spomenka Kobe, substantially contributed to the success of the JSI team. Fundamental research was the basis for a highly innovative technology, developed within the department. The technology is based on electrophoretic deposition and a sophisticated heat-treatment method for selective diffusion along the grain boundaries of the magnet. This technology has resulted in the project’s ambitious target magnetic properties being achieved. The process is now in the testing stage at Vacuumschmelze’s pilot line in Hanau, Germany. The final result will be high-energy magnets with the minimum content of valuable heavy rare earths. These magnets will be used in a prototype Siemens demonstrator motor for wind turbines as part of the ROMEO project.
The Austrian institute Joanneum Research held its FORUM ROBOTICS on 21 January 2015 in Graz, Austria. The plenary lecture entitled "Robots can learn!" was presented by Prof. Jadran Lenarčič, Director of the Jožef Stefan Institute, in which he described the latest advances in the area of robotics as well as his vision of the future. Among the attendees were prof. Wolfgang Prybil, President of Joanneum Research, and Mr Christopher Drexler, a member of the Provincial Government of Styria.
The Jožef Stefan Institute and Joanneum Research have been actively collaborating across a variety of fields since 2005, when the original collaboration agreement was signed. Joanneum Research has recently opened a new robotics division in Klagenfurt, Austria, which will create excellent opportunities for joint research and technology development projects.
On 22 December 2014 the journal Nature Physics published an article entitled Light-controlled topological charge and a Nematic Liquid Crystal , written by Maryam Nikkhou, Miha Škarabot, Simon Čopar, Miha Ravnik, Slobodan Žumer and Igor Muševič, from the Department for Solid-State Physics (F5) of the Jožef Stefan Institute and the Faculty of Mathematics and Physics, University of Ljubljana. Their paper describes experiments in which a strong laser light is used to create and stabilize a pair of topological defects in liquid crystals formed by a defect and an anti-defect or a "particle" and an "antiparticle". The picture shows the liquid crystal, as seen under a microscope, only a few milliseconds after the laser pulse. This pulse leads to the formation of a dense network of topological defects, from which eventually pairs of topological defects are formed. This is reminiscent of the Kibble-Zurek mechanism for the production of monopoles in cosmology. This means that by using the theory of the dynamics of the provisions for annihilation and basic topological rules we can observe the mechanisms for the production topological charge.
Members of the Jožef Stan Institute’s Department of Theoretical Physics (F1), Luca Tubiana and Rudolf Podgornik, as well as a former members Anze Losdorfer Bozic and Christian Micheletti of La Scuola Internazionale Superiore di Studi Avanzati (SISSA) in Trieste, have recently published a paper entitled Synonymous Mutations Reduce Genome Compactness in Icosahedral ssRNA Viruses in the latest issue of Biophysical Journal (108 194–202 2015). The paper discusses the effect of synonymous mutations – mutations that do not change the protein complement – on the size of the folded RNA molecule, proving that even a very restricted phase space of synonymous mutations is still rich enough to support variations in the size of the RNA. The paper was also featured on the cover of the journal and commented on in the “New & Notable” section of the journal by A. Ben-Shaul and W.M. Gelbarta, "Viral ssRNAs Are Indeed Compact”. The paper was also featured on the blog phys.org as well as several other science news outlets.
On 9 January 2015 the Jožef Stefan Institute and the French Centre National de la Recherche Scientifique (CNRS) signed an agreement on a common International Associated Laboratory (LIA). The main research themes of the new laboratory are quasicrystals and complex alloys, with the aim being to find answers to unsolved, fundamental questions: how and why does the complexity arise, what is the underlying mechanism for the promotion of complexity, is this mechanism unique and what is relation between the electronic and atomic structures of the crystal?
The LIA will not only contribute to a better understanding of the complexity in the development of some metallic alloys, which in a way is still at the beginning, but will also encourage physical metallurgy at the frontiers of knowledge related to the physics of solids and inorganic chemistry.