News Archive

This year's winners of the Slovenian highest awards for science were presented on December 1, 2020, in a documentary Highlights of Slovenian Science through the eyes of award winners for outstanding achievements 2020. One of the award winners is prof. dr. Samo Kralj from the Condensed Matter Physics Department who received the Zois Certificate of Recognition for important research achievements in the field of soft matter physics. Congratulations!

Dr. Simon Čopar form the Faculty of Mathematics and Physics, University of Ljubljana, and dr. Uroš Tkalec from the Condensed Matter Physics Department at the »Jožef Stefan« Institute in collaboration with Korean researchers led by Dong Ki Yoon have published article Periodic Arrays of Chiral Domains Generated from the Self-Assembly of Micropatterned Achiral Lyotropic Chromonic Liquid Crystal in the ACS Central Science. The article includes both the experimental demonstration and theoretical explanation of the phenomena and is an important contribution towards practical use of chiral structure made from water-based non-chiral LC-molecules. It was highlighted on the front page of the November issue of the journal, which also included a commentary by Oleg Lavrentovich from Kent State University.

Led by dr. Janez Štrancar, PhD, the researchers of the Biophysics Laboratory of the Condensed Matter Physics Department at the “Jožef Stefan” Institute have made crucial contributions to a large study of the mechanisms for nanomaterial toxicity and inflammation predictions without the use of test animals, published in the Advanced Materials under the title Prediction of Chronic Inflammation for Inhaled Particles: the Impact of Material Cycling and Quarantining in the Lung Epithelium. As part of the SmartNanoTox Horizon 2020 Projects, the Biophysics Laboratory coordinated the work of 34 authors from 9 countries. The authors of the article are the first to identify the key molecular events involved and connect them into a complicated cyclic mechanism that triggers different inflammatory responses. This knowledge allowed them to develop a model for predicting chronic inflammations using only selected cell tests. These findings are already being used to develop autonomous detection systems to predict the safety of materials, chemicals, medications or vaccines.

As the beginning of the COVID-19 pandemic caused a general lack of medical protective equipment, the researchers from “Jožef Stefan” Institute, including associates of our department, decided to look into the option of using ionizing radiation to sterilize used masks and allow their reuse. The results showed that facepiece respirators type FFP2 and FFP3 can be sterilized by Gamma irradiation and electron beam irradiation. This method of sterilization preserves the mechanical and chemical characteristics of masks and does not harm the efficiency of aerosol particle filtration. While 20 kGy radiation does cause the loss of the polypropylene membrane filters static charge, re-application of the charge brings the filtration efficiency back to the previous level. Masks can be sterilized up to two times using this method. The research was carried out by Luka Pirker, Anja Pogačnik Krajnc, Anton Gradišek, Andreja Jelen, Maja Remškar, Igor B. Mekjavić, Janez Kovač, Miran Mozetič, Luka Snoj, Jan Malec and Vladimir Radulović, and the results were published in the Journal of Membrane Science in the article entitled Sterilization of polypropylene membranes of facepiece respirators by ionizing radiation.

Abdou Hassanien from the F5 Department of Jozef Stefan Institute has published, in collaboration with Biao Zhou and Akiko Kobayashi from Nihon University, Tokyo, Japan, an article in the Journal of Advanced Electronic Materials titled Spontaneous Antiferromagnetic Ordering in a Single Layer of (BETS)2GaCl4 Organic Superconductor. The fabrication of such well-defined and atomically clean interfaces between materials of different orders are of fundamental interest to engineer novel functionalities and to study emergent phenomena in condensed matter physics. The paper illustrates the interplay between electronic orders of hybrid mix of nested antiferromagnetic molecular chains and superconducting molecular stripes at the single layer limit. Results of low temperature scanning tunneling microscopy and spectroscopy have shown that low level vibronic and magnetic excitations that dominate the higher temperature phase are absent below Tc which point to their cooperative existence and possible renormalization to mediate superconductivity in such d-wave superconductors.

Guilhem Poy from Faculty of Mathematics and Physics at University of Ljubljana and Slobodan Žumer from Jozef Stefan Institute in collaboration with the group of Ivan Smalyukh from University of Colorado in Boulder in Physical Review X published the paper that Control of Light by Topological Solitons in Soft Chiral Birefringent Media, was highlighted in APS Physics Focus by the editorial article “Liquid-Crystal Vortices Focus Light”. Topological solitons appearing in different areas of physics are fascinating localized perturbations of ordering fields enjoying topological protection. The authors demonstrate refraction, reflection, and lensing of weak laser beams by various topological solitons in frustrated chiral nematics and show how interactions of light with such topological solitons are well described using a generalized Snell’s law and ray-tracing models. These may lead to new means for controlling flow of light for use in optics and photonics.

Slobodan Žumer from Jozef Stefan Institute and Guilhem Poy from Faculty of mathematics and Physics at University of Ljubljana in collaboration with Andrew Hess and Ivan Smalyukh from University of Colorado in Boulder published the paper Chirality-enhanced periodic self-focusing of light in birefringent soft media in Physical Review Letters. It presents numerical, experimental and theoretical evidence of chirality enhanced nonlinear optical response of frustrated chiral nematics. In achiral nematics, the reorientation of molecules around laser beams with appropriate power is responsible for the generation of spatial optical solitons called "nematicons". In unwounded chiral nematics, the frustration caused by a confinement incompatible with their lowest-energy states allows a relatively weak light to locally destabilize the initially uniform orientational fields and thus boost their nonlinear optical responses. Our research findings are expected to allow new self-focusing based applications.

As a member of an international consortium, “Jožef Stefan” Institute received the European Athena project, whose aim is the implementation of gender equality plans to release the potential of research institutions in Europe. The F5 department will have an active role in this project, joined by 9 other “Jožef Stefan” Institute departments (U1, F4, K1, K3, K5, K7, E3, E5 and E7). Despite the large number of highly qualified women with degrees, women make up only a third of research workforce in the EU. The aims of this project are to remove the barriers that make it difficult for women to become employed in a research facility and to be promoted to researchers, to strengthen the presence of the gender dimension within research programs and to address the gender inequality in decision making. The two main project goals are development and implementation of a plan for gender equality on a systemic, institutional level. The members of the international consortium are research institutions from Central and Eastern Europe and from remote regions with a low gender equality index, as the project aims to reduce the gap between research organizations across Europe.

Tina Arh, Matjaž Gomilšek, Matej Pregelj, Martin Klanjšek and Andrej Zorko from the Solid State Physics Department and Peter Prelovšek from the Department of Theoretical Physics at the “Jožef Stefan” Institute, in collaboration with researchers from United Kingdom, USA and China, have published a paper “Origin of Magnetic Ordering in a Structurally Perfect Quantum Kagome Antiferromagnet” in Physical Review Letters. They confirmed more than a decade old theoretical prediction of a quantum critical point of a kagome antiferromagnet between a quantum spin liquid and a magnetically ordered state, induced by the Dzyaloshinskii-Moriya magnetic anisotropy. YCu3(OH)6Cl3 is the first known material with a perfect kagome lattice without any impurities, in which the magnetic anisotropy can be studied in isolation from other perturbations. Understanding the mechanism of magnetic ordering in this material is crucial for understanding the stability of enigmatic quantum spin liquids.

During a football match at the Stožice Stadium in Ljubljana in 2019, the F5 department researchers measured nanoparticle air pollution. During the match, the fans of both teams used pyrotechnic devices to support their teams despite the prohibition. Researchers of the Department of Condensed Matter Physics, Luka Pirker, Anton Gradišek, Bojana Višić and Maja Remškar discovered the number of nanoparticles in the range between 30 nm to 300 nm increased by 1200 percent when flares were light and the players inhaled 300 % more particles than usual. In addition to carbon, the chemical analysis also showed the presence of potentially poisonous elements which are used for colouring and as fuel such as strontium (red colour), barium (green colour), potassium, magnesium and chloride. The findings were published in the Atmospheric Environment journal.

Andrej Zorko from the Department of Condensed Matter Physics at Jožef Stefan Institute and the Physics department at the Faculty of Mathematics and Physics, University of Ljubljana, was part of the international research team that confirmed the gapless ground state in the archetypal quantum kagome antiferromagnet ZnCu3(OH)6Cl2. Their research, which was published in the Nature Physics journal, disproved the decades old conviction that a spin-gap must exist in this material and shone new light on the enigmatic state of this spin liquid. This experimental conclusion aligns with the most recent theories which propose a gapless Dirac spin liquid as the ground state of the Heisenberg kagome antiferromagnet.

A team of researchers from the Faculty of Mathematics and Physics and Faculty of Medicine, University of Ljubljana, and »Jožef Stefan« Institute, including Uroš Tkalec from our department, have studied previously unresearched dynamic chiral states which arise before the homeotropic to flow-aligned transition. In the article published in the Nature Communications journal, they explain the mechanism of phase transitions between topologically different states of pressure driven liquid crytal with a phenomenological model based on the anisotropy of elastic constants and completed the phase diagram of all observed hydrodynamic states. These concepts could also be used in lyotropic and active nematic liquids with nematic order.

Simon Čopar, Jure Aplinc, Žiga Kos, Slobodan Žumer and Miha Ravnik, researchers from the Department of Condensed Matter Physics and the Physics Department of the Faculty of Mathematics and Physics, University of Ljubljana, were the first team who managed to research the topology of three-dimensional active nematic turbulence under the spherical confinement. Based on mesoscopic imaging, they used numerical modeling to show the dynamics in active nematics – usually complex biological liquids, in which the particles propel themselves using energy they receive from the environment. The team described the complex chaotic dynamic of active turbulence using topological events that govern the defects appearing in such matter. They also demonstrated coupling of surface and bulk topological defect dynamics by changing from strong perpendicular to in-plane surface alignment. This article, published in Physical Review X, importantly contributes to our understanding of the quickly evolving field of active soft matter.

At the international conference European C-MetAC Days 2019, held in December 2019 at the Max Planck Institute for Chemical Physics of Solids in Dresden, Germany, Darja Gačnik received the award for the best oral presentation in the young scientists’ category. In her presentation Superconductivity in Ti–Zr–Hf–(Sn,Ni,Nb) high-entropy alloys she presented her research of superconductivity in a new type of metal alloys, called high-entropy alloys. The research results she presented were uncovered in collaboration with her co-workers at the Department of Condensed Matter Physics (S. Vrtnik, A. Jelen, M. Krnel, P. Koželj, J. Dolinšek) and dr. Qiangom Hujem from the Institute of Applied Physics at the Jiangxi Academy of Sciences, Nanchang, China.

An article conceptualised by Abdou Hassanien, associate Department of Condensed Matter Physics at the “Jožef Stefan” Institute, and co-written by Alexander Vahl, Niko Carstens, Thomas Strunskus in Franz Faupel from the Christian-Albrechts-University of Kiel, Germany, was published by Scientific Reports. The article describes behaviour of memristors (memory resistors) at the level of individual nanoparticles to find the best conditions for robust operation of devices. Their discoveries also help understand the underlying physical mechanisms. Furthermore, they discovered that application of alloy nanoparticles effectively limits the formation of stable metallic filaments and results in reproducible diffusive switching characteristics.

Jean-Pierre Bourguignon, president of the European Research Council, visited Slovenian for the third time on November 28, 2019. In the morning he visited the Faculty of Mechanical Engineering at the University of Ljubljana. In the afternoon he met with representatives of the “Jožef Stefan” Institute, primarily with the ERC grant winners, dr. Dragan Mihailovič and our own dr. Matjaž Humar. He also visited the laboratories of the Department for Condensed Matter Physics where dr. Humar’s Cell Lasers Project is being undertaken. In addition to boosting the international visibility of the researchers, the ERC grants also allow them to implement several years of independent research at the highest level, including the acquisition of the necessary research equipment.

On November 20, 2019, the Republic of Slovenia awarded the highest prizes and awards for outstanding achievements in science, research and development to 18 top scientists. Among them were two associates of the Department of Condensed Matter Physics. Professor dr. Desnis Arčon received the Žiga Zois prize for outstanding achievements in the fields of quantum magnetism and unusual superconductivity and assistant professor dr. Miha Ravnik received the Žiga Zois Award for outstanding achievements in the field of soft matter physics.

Professor dr. Nives Ogrinc from the Department of Environmental sciences and professor dr. Boris Rogelj, head of the Department of Biotechnology were also among the 18 awarded scientists.

Brigita Rožič, researcher of the Department of Condensed Matter Physics at the “Jožef Štefan” Institute, has received the Fulbright grant for her excellent scientific and research work. The Fulbright grant is awarded every year to successful scientists from all over the world. In Slovenia this grant is awarded by the US Embassy in Ljubljana as part of the Fulbright programme financed by the US government. The grant further inspired dr. Rožič for her future research and increased her visibility as well as the visibility of the “Jožef Štefan” Institute. The grant allowed her to do research at the Case Western Reserve University with prof. Charles Rosenblatt’s team, working in an area that was entirely new to her. Furthermore, she loved living in Cleveland, whose many lakes and wonderful environment reminded her of home. Dr. Rožič also received congratulations for the award from the president of the United States.

Dr. Martin Klanjšek, associate of the F5 Department, was awarded the Blinc Award for Extraordinary One-time Achievements for proving the existence of unusual quasiparticles called anyons.

On October 24, 2019, the Faculty of Mathematics and Physics of the University of Ljubljana and the “Jožef Stefan” Institute awarded the first Blinc awards for research and theoretical work in physics. The awards were founded to celebrate the best physicists and to commemorate Robert Blinc, one of the sharpest Slovenian researchers and a member of the Slovenian Academy of Science and Arts.

Two other awards were bestowed in addition to the Blinc Award for Extraordinary One-time Achievements: prof. dr. Matjaž Perc from the Faculty of Natural sciences and Mathematics was awarded the Blinc Award for Physicist at the Beginning of their Career and prof. dr. Peter Prelovšek, the most visible Slovenian researcher in the field of theoretical physics of condensed matter in Slovenian and abroad, received the Blinc Award for Lifetime Achievement.

Dr. Matjaž Humar, head of the Bio-integrated photonics lab and associate of the Condensed Matter Physics Department at the Jožef Stefan Institute was awarded the prestigious ERC Starting Grant by the European Research Council in the amount of 1.5 million Euro. The aim of the Cell Lasers Project is to study the interactions between lasers inserted into individual cells and the biological processes within those cells. Dr. Humar recently presented the first example of a laser within a living cell. Previous research has shown that lasers can operate within cells, but it has not yet been researched how the operation of lasers interacts with biophysical and biochemical processes of the cell. In the long term, the Cell Lasers Project aims to transform lasers within cells from a scientific curiosity into a robust method that can be used in the fields of research and medicine.

The International Conference on Quasicrystals – ICQ14 took place in Kranjska Gora from May 26 to May 31, 2019. It was attended by 120 scientists from 18 countries and three continents (Europe, Asia and America). Dr. Andreja Jelen of the F5 Department also attended the conference, where she presented the poster “Microstructure and magnetic properties of a single-crystalline FeCoCrMnAl high-entropy alloy”. The committee of three scientists from France, Japan and Poland selected her poster as the best poster contribution at the ICQ14 conference. The Best Poster Prize was sponsored by the Crystals journal. The photo shows dr. Andrej Jelen and the president of the committee, prof. Hiroyuki Takakura from the University of Hokkaido, Japan.

On 4 July 2017, the third Conference of young researchers and students was held at the "Jožef Stefan Institute", under the honorary patronage of academician Tadej Bajd, president of the Slovenian Academy of Sciences and Arts. In the morning, the present ministers and the hosts stressed the importance of circulation of knowledge, ideas and practices among the young in Slovenia, across the borders and abroad. Then Matjaž Humer from the Deparment of Condensed Matter Physics and Igor D. Gregorič, cardiovascular surgeon who has been operating in the USA for the last 30 years, presented their career paths as an inspiration for future generations. In the afternoon, numerous participants talked about topics such as a successful career path as a challenge for the next generation, the opportunity presented by exchanges, the challenge of finding employment for young Slovenes abroad and networking of young Slovene researchers.

Brigite Rožič, associate of the Department of Condensed Matter Physics, published a paper titled Oriented Gold Nanorods and Gold Nanorod Chains within Smectic Liquid Crystal Topological Defects  in the renown scientific journal ACS Nano. Gold nanorods attracted a lot of interest thanks to their unique optical characteristics based on the localised surface plasmonic resonance and to the many options for their application. However, for maximum efficiency, gold nanorods must be well ordered. B. Rožič, in collaboration with scientists form France, Germany and the USA, was among the first to prove that smectic liquid-crystal defects can be used to organise gold nanorods of different sizes into ordered superstructures and create a new efficient plasmonic system. This even more options for application of gold nanorods  for example in optics and photonics.

The Nature Communication journal published the article Hidden topological constellations and polyvalent charges in chiral nematic droplets by Gregor Posnjak, Simon Čopar and Igor Muševič, associates of the F5 Department for Condensed Matter Physics at the J. Stefan Institute and the Faculty for Mathematics and Physics at the University of Ljubljana. The authors were the first in the world to reconstruct the order of molecules in micrometer-sized droplets of chiral nematic liquid crystal, for which they used a state-of-the-art method of 3D fluorescent confocal microscopy, and discovered divers topological states, including chins of topological defects and point defects with a multiple of the basic topological charge. The ordering of the molecules around these topological defects is similar to the atoms with high valence and enables the construction of complex topological molecule-like structures.

The associates of the »Jožef Stefan« Institute, Melita Sluban (F5), Polona Umek (F5) and Jernej Iskra (K3), in collaboration with the researchers from the University of Ljubljana (Faculty of chemistry and chemical technology) and the University of Bucharest, for the first time successfully catalysed the aldol condensation, which is the most common reaction for creation of new carbon-carbon bonds, using protonated titanate nanotubes. Such a reaction is a 'green' alternative to the current industry practice of using stoichiometric amounts of homogeneous catalyst, which cannot be recycled after the reaction ends. In contrast, when using protonated titanate nanotubes, a mere catalytic amount of material ensures a successful reaction, the catalyst can be used several times and it was even successful in a large-scale experiment. The work was published in the article Protonated titanate nanotubes as solid acid catalyst for aldol condensation in the Journal of Catalysis, one of the lead journals in the field of catalysis.

On January 24, 2017,  Nature Communications published a paper called Fractal Nematic Colloids written by Uroš Jagodič, Igor Muševič and Miha Ravnik, associates of the Department for Condensed Matter Physics (F5) at the "Jožef Stefan" Institute and of the Faculty of Mathematics and Physics at the University of Ljubljana in collaboration with the associates of the Sharif University of Technology in Iran. They used two-photon laser lithography to create colloidal particles in the shape of fractal Koch stars, which they studied in liquid crystal. The fractal particles influence the ordering of the liquid crystal and create topological defects, whose number increases exponentially in accordance with the fractal order of particles. This is the first time that fractal states were created in soft matter.

The Physical Review Letters published a paper called Low-Temperature Global Symmetry Reduction in the Kagome Antiferromagnet Herbertsmithite by Andrej Zorko and Matjaž Gomilšek, associates of the Department for condensed matter physics at the "Jožef Stefan" Institute. In collaboration with groups from Croatia, USA and France, they were the first to observe symmetry brake in a Herbertsmithite crystal, which is known as the paradigm of a quantum antriferromagnet on a Kagome spin lattice, where the theory predicts a magnetic disordered ground state of spin liquid. Such break could hold the key information on the essential nature of the magnetic ground state of this crystal. After more than a decade of intensive research, this discovery offers a completely new insight into the enigmatic ground state of a spin liquid on a Kagome spin lattice.