Entries by Polona Brajer

Nonequilibrium Quantum Dynamics and Relaxation Phenomena in Many Body Systems, December 16 – 19, 2018, Krvavec, Slovenia

Nonequilibrium Quantum dynamics is becoming one of the most advanced contemporary research areas in solid state physics, ultracold atoms, nano physics and quantum devices. Understanding of such dynamics in real world systems presents a challenge to experimentalists and theory alike. The time-evolution of many-body quantum systems can be viewed as the time-evolution of quantum information, […]

Splay Nematic Phase

Researchers from the Department for Complex Matter Jožef Stefan Institute Alenka Mertelj, Nerea Sebastián, Luka Cmok in Martin Čopič have in collaboration with researchers from University of York, UK, studied a recently designed nematic phase, which appears in materials made of polar wedge-shaped molecules. They discovered that average molecular orientation in the new phase organizes […]

Aleksander Yu. Kuntsevich, 22.11.2018 at 11:00, F7 Seminar room

SrₓBi₂Se₃-nematicity, superconductivity, crystals and thin films Aleksander Yu. Kuntsevich, P. N. Lebedev Physical Institute, Moscow, Russia Abstract: 3D topological insulator Bi₂Se₃ attracts much attention as a platform for future low consumption spintronics and quantum computations. Recently, nematic (and possibly topological) superconductivity was discovered in AₓBi₂Se₃, where A = Cu, Sr, Nb. In my talk I will […]

Andrej Kranjec, 13.11.2018 at 14:30, F7 Seminar room

Vertex directed analysis of the hidden state relaxation in 1T-TaS2 Andrej Kranjec, Department for Complex Matter, JSI Abstract: I will be presenting a brief summary of our latest results obtained by applying a global interdomain shifts recognition algorithm on a high quality STM sequence of the relaxation of the H-state in 1T-TaS2. We show how the […]

Prof. Dr. Michele Fabrizio, 4.10.2018 at 13:00, Physics seminar room

Transient cooling of quasiparticles in K3C60  by mid-infrared laser pulses   Prof. Dr. Michele Fabrizio, International School for Advanced Studies SISSA, Trieste, Italy Abstract: We propose an explanation of the transient superconducting-like optical behavior observed at temperatures as high as ten times Tc in K3C60 irradiated by mid-infrared laser pulses.  In our theory the phenomenon is due […]

Mimoza Naseska, 19.9.2018 at 13:00, F7 Seminar room

Spin density wave dynamics in iron based pnictides  Mimoza Naseska, Department of Complex Matter, JSI Abstract: We present ultrafast optical time-resolved spectroscopy measurements of the ultrafast system trajectory through the spin density wave (SDW) phase transition in SrFe2As2 and EuFe2As2. Using the standard pump-probe technique we determined the threshold fluence for the nonthermal destruction of […]

Maria D’Antuono, 18.7.2018 at 13:00 in F7 Seminar room

Magnetotransport properties of 2DEG formed in LAO/ETO/STO heterostructures studied using the electric field effect Maria D’Antuono, University of Naples Federico II, Naples, Italy Abstract: In 2004 Ohtomo and Hwang reported the formation of a high mobility 2-dimensional electron gas (2DEG) at the interface between two wide bandgap insulators oxides, namely LaAlO3 (LAO) and SrTiO3 (STO). In […]

Vitomir Sever, 6.7.2018 at 13:00 in F7 Seminar room

Study of the efficiency of the solar updraft tower as a function of its height Vitomir Sever, Material Science and Engineering Department at Institute National des Sciences  Appliquées (INSA), Lyon Abstract: With the constant increase in pollution, the need to find new systems that provide clean energy becomes more and more important. One of these […]

Dr. Satoshi Tsuchiya, 22.6.2018 at 13:00 in F7 Seminar room

Spectrally resolved and three pulse pump-probe spectroscopy in strongly correlated organic conductors Dr. Satoshi Tsuchiya, Complex Matter Department, Jozef Stefan Institute, Slovenia; Department of Applied Physics, Hokkaido University, Japan Abstract: The series of k-(BEDT-TTF)2X (X: anion molecules) has attracted much interest in fundamental physics related with strong electron correlation and application of devices because of a rich […]

Koichi Nakagawa, 1.6.2018 at 13:30 in the Physics Seminar room

Polarized pump-probe measurements in organic superconductors near Mott boundary Koichi Nakagawa, Department of Applied Physics, Hokkaido University, Sapporo, Japan Abstract: A series of κ-type organic superconductors offers an ideal electronic system to investigate crucial electronic properties such as pseudogap and fluctuating superconductivity, for understanding mechanism of unconventional superconductivity since chemical substitution in insulating/conducting molecules can lead to […]

Asst. Prof. Dr. Hiroyoshi Nobukane, 1.6.2018 at 13:00 in the Physics Seminar room

High-Tc superconductivity in ruthenates Asst. Prof. Dr. Hiroyoshi Nobukane, Department of Physics, Hokkaido University, Sapporo, Japan Abstract: Layered perovskite materials can control quantum states from superconductivity to a Mott insulator by tuning physical and chemical pressure. By reducing the thickness of a layered crystal to nanometer range, a nanofilm due to a negative pressure effect leads to […]

Jaka Vodeb, 25.5.2018 at 13:00 in F7 Seminar room

Charged lattice gas of polarons in 1T-TaS2 Jaka Vodeb, Department for Complex Matter, Jozef Stefan Institute, Ljubljana, Slovenia Abstract: Motivation for this work comes from the discovery of a new metastable amorphous (A) state in 1T-TaS2 (TAS)1. The A state represents a disordered polaron pattern, which exhibits metallic behavior. We employed a classical charged lattice […]

Michele Diego, 17.5.2018 at 11:00 in F7 Seminar room

Out of equilibrium electronic properties of ZrTe5 Michele Diego, Department of Complex Matter, JSI Abstract: Transition metal pentatelluride, ZrTe5, displays a set of unique and exotic transport properties, which make this material an ideal candidate for magnetic and thermoelectric devices. In particular, the best known anomaly is its resistivity trend, which shows a metallic behavior […]

Matjaž Ličen, 20.4.2018 at 13:00 in F7 Seminar room

Photoregulating the self-assembly of lipophilic guanosine derivaters at the air-water interface Odsek za kompleksne snovi, IJS Abstract: Basic blocks of DNA are very interesting constituents for designing supramolecular single-layer and multilayer surface  architectures. Our recent studies of self-assembly of nucleoside derivatives in monolayer films at the air-water interface (Langmuir films) reveal that guanosine derivatives exhibit […]

Hidden quantum resistance of a superconductor nanowire, Science Advances

Superconductors are known for zero electrical resistance, which is one of the consequences of superconductivity as a macroscopic quantum phenomenon. However, in an unusual experiment on extremely narrow superconducting nanowires performed by Ivan Madan and Jože Buh under the leadership of Dragan Mihailovic, the superconductor is switched by ultrashort laser pulses to a hidden metastable […]

Dr. Andrey Leontyev, 12.4.2018 at 13:00 in F7 Seminar room

Nonresonant multi-pulse selective spectroscopy of interaction-induced responses in liquids using optical Kerr effect Kazan E.K. Zavoisky Physical-Technical Institute, Kazan, Russia Abstract: An ultrafast selective spectroscopic measurements of vibrational-rotational dynamics of molecules in liquids were implemented using optical Kerr effect (OKE) detection under multi-pulse nonresonant xcitation. Introducing additional excitation pulses and creating either constructive or destructive […]

Matej Prijatelj, 23.3.2018 at 13:00 in F7 Seminar room

Expansion of transition metal dichalcogenides Hella Saturnus Slovenija d.o.o., HSS – Ljubljana Abstract: Layered two-dimensional materials have unique physical and chemical properties due to their highly anisotropic nature. A few of the layered crystals can be further expanded to low density / high specific surface area materials by introducing molecules to the inter planar spaces. […]

Prof. dr. Roman Sobolewski, 16.3.2018 at 13:00 in the Physics Seminar room

Nanostructured superconducting single-photon detectors as photon energy, number, and polarization resolving devices Departments of Electrical and Computer Engineering and Physics and Astronomy, and the Materials Science Program and Laboratory for Laser Energetics, University of Rochester, Rochester, NY Abstract: We present an overview of the physics of operation of superconducting single-photon detectors (SSPDs) and their implementation […]

Field-controlled structures in ferromagnetic cholesteric liquid crystals

One of the advantages of anisotropic soft materials is that their structures and, consequently, their properties can be controlled by moderate external fields. Whereas the control of materials with uniform orientational order is straightforward, manipulation of systems with complex orientational order is challenging. We show that a variety of structures of an interesting liquid material, […]

Tinkara Troha, 14.09. 2017 at 13:00, Seminar room F7

UV second harmonic generation in structured AIN optical wavequides Tinkara Troha Fakulteta za matematiko in fiziko in Institut »Jožef Stefan«, Ljubljana Abstract: We investigated the potential of aluminium nitride (AlN) for generation of UV light through a nonlinear optical process of second harmonic generation (SHG). AlN is an excellent candidate since it is transparent to […]

Dynamic Magneto-optic Coupling in a Ferromagnetic Nematic Liquid Crystal, Physical Review Letters, 01.09.2017

Hydrodynamics of complex fluids with multiple order parameters is governed by a set of dynamic equations with many material constants, of which only some are easily measurable. We present a unique example of a dynamic magneto-optic coupling in a ferromagnetic nematic liquid, in which long-range orientational order of liquid crystalline molecules is accompanied by long-range […]

Mimoza Naseska, 11.09. 2017 at 13:00, Seminar room F7

Ultrafast spin density wave dynamics at intense optical pulse excitation Mimoza Naseska Fakulteta za matematiko in fiziko in Institut »Jožef Stefan«, Ljubljana Abstract: Ultrafast time-resolved optical spectroscopy has become an important tool for characterizing the various energy transfer processes occurring after absorption of intense laser pulses. The relaxation timescales observed after photoexcitation can in some […]

Jaka Vodeb, 08.09.2017 at 13:00, Seminar room F7

Urejanje polaronov v dveh dimenzijah Jaka Vodeb Fakulteta za matematiko in fiziko in Institut »Jožef Stefan«, Ljubljana Abstract: V magistrski nalogi je obravnavano modeliranje nizkotemperaturnih faz kristala 1T-TaS$_2$ (TAS). V splošnem je za kristal TAS značilen bogat fazni diagram in mikroskopska struktura pojava vala gostote naboja (VGN). Do sedaj je bilo možno mikroskopsko teorijo povprečnega […]

Best Poster Award at QCM 2018 for Mimoza Naseska

Young researcher Mimoza Naseska was awarded Best Poster Award at the International Workshop Quantum Complex Matter (QCM 2018) and Frontiers Condensed Matter Physics (FCMP),  June 11-15, 2018, Rome, Italy for poster “Optical quench and recovery of SDW state SeFe2As2 and EuFe2As2”.

10th Liquid Matter Conference, 17-21 July 2017, Ljubljana, Slovenia

The conference will be held from July 17 through 21 2017 at the Cankarjev dom Cultural and Congress Centre in Ljubljana, Slovenia. Previous conferences in the series were hosted by Lyon (1990), Florence (1993), Norwich (1996), Granada (1999), Konstanz (2002), Utrecht (2005), Lund (2008), Vienna (2011) and Lisbon (2014). The purpose of the conference is […]

Dr. Ljupka Stojčevska Malbašić; Best poster award at the conference ICFSI 2017, Hannover, Germany (02.-07.07.2017)

Dr. Ljupka Stojčevska Malbašić received the Best Poster Award at the 16th International Conference on the Formation of Semiconductor Interfaces (ICFSI 2017), for her paper: Study of the photoinduced hidden state in 1T-TaS2 single crystals doped with selenium by means of time-resolved photoemission spectroscopy (Co-authors from JSI; Asst. Prof. Tomaž Mertelj, Prof. Dr. Dragan Mihailović […]

prof. dr. Xinzheng Zhang, 22.06.2017 at 13:00, Seminar room F7

Control of Light Field Based on Liquid Crystal/Polymer Composite Structures prof. dr. Xinzheng Zhang TEDA Institute of Applied Physics & School of Physics, Nankai University, P. R. China Abstract: Liquid Crystal/Polymer Composites (LCPCs) consisting of liquid crystal (LC) and polymer are a new class of functional materials. They possess excellent anisotropy and reconfigurability by external fields. In composites, the polymer plays a role […]

Prof. dr. Rupert Schreiner, 15.06.2017 at 13:00, Seminar room F7

Semiconductor Field Emission Electron Source for Application in Sensors and X-ray Sources prof. dr. Rupert Schreiner Ostbayerische Technische Hochschule Regensburg, Fakultät Allgemeinwissenschaften und Mikrosystemtechnik, Germany Abstract: Semiconductor field emitter arrays are suitable candidates for applications which require a very stable field emission (FE) current and a high emission uniformity over the entire emission area. By […]

Peter Topolovšek, 24.05.2017 at 14:00, Seminar room F7

Nanometric thin organic and inorganic layers and their use in perovskite solar cells and elastomers Peter Topolovšek Jožef Stefan International Postgraduate School, Ljubljana Invitation and abstract [PDF] Abstract: Realization of highly performing vertically built opto-electronic devices typically requires a close control over the thickness of the constituing layers in order to find the balance between […]

Tetiana Borzda, 18.05.2017 at 13:00, Seminar room F7

Non-equilibrium electron dynamics in semiconducting transition metal Tetiana Borzda Jožef Stefan International Postgraduate School, Ljubljana Invitation and abstract [PDF] Abstract: In the talk I will discuss equilibrium and non-equilibrium optical properties of two-dimensional materials, in particular transition metal dichalcogenides (TMDs) such as MoS2 and WSe2. After an introduction to TMD materials and their photophysics as […]

Miloš Borovšak, 17.05.2017 at 13:00, Seminar room F7

Phase changes in molybdenum oxides induced by AFM tip and laser excitation Miloš Borovšak Faculty of Mathematics and Physics, Ljubljana Abstract: Molybdenum oxides show many physical properties, especially electronic, that are similar to the physical properties of 1T-TaS2, where a phase transition from insulator to metal can occur with a single ultrashort laser pulse, and […]

March for Science

Scientists against research funding cuts: http://4d.rtvslo.si/arhiv/dnevnik/174467019 http://m.24ur.com/novice/slovenija/foto-v-ljubljani-protestirali-zaradi-krcenja-sredstev-za-raziskave-in-inovacije.html http://www.zurnal24.si/shod-za-znanost-raziskovalke-in-raziskovalci-zahtevajo-boljse-pogoje-clanek-289280 http://www.vecer.com/v-ljubljani-shod-za-znanost-za-1-odstotek-bdp-ja-6258132 http://www.delo.si/znanje/znanost/shod-za-znanost.html?iskalnik=Shod%20za%20znanost svet24.si/clanek/novice/slovenija/58f77e74a8801/protesnti-shod-za-znanost-podprl-tudi-brglez https://marijanzlobec.wordpress.com/2017/04/19/junasko-mirno-shod-za-znanost/ http://www.publishwall.si/casopisvecer/post/285674/v-ljubljani-shod-za-znanost-ministrica-ga-podpira-kot-znanstvenica  

Slovenian Research Agency – NEW PROJECTS APPROVED, 2017

Femtosecond time-resolved scanning tunneling electron microscopy of complex materials, 01.05.2017 – 01.05.2020, prof. dr. Dragan Mihailović Electrically tunable ferromagnetic liquids, 01.05.2017 – 01.05.2020, asst. dr. Alenka Mertelj Magnetically reconfigurable elastomeric optical surfaces, 01.04.2017 – 31.03.2019, prof. dr. Dragan Mihailović, prof. dr. Irena Drevenšek Olenik ARRS Results [link]

A possible boost for integrated photonics from the labs of the Jožef Stefan Institute

Fibre optical communication is increasingly replacing traditional electrical interconnects due to its higher speed and energy efficiency: A possible boost for integrated photonics from the labs of the Jožef Stefan Institute Abstract: A possible boost for integrated photonics from the labs of the Jožef StefanInstitute Fibre optical communication is increasingly replacingtraditional electrical interconnects due to its […]

Victor Vega Mayoral, 11.01.2017 at 14:00, Seminar room F7

Photophysics of transition metal dichalcogenides obtained from liquid phase exfoliation Victor Vega Mayoral Trinity College Dublin, Dublin, Ireland Abstract: Two research lines are presented in this seminar. The first one is focused on exfoliating WS2 via liquid phase exfoliation and the use of some basic, commonly available and fast characterization techniques. Exfoliation in water/polymer dispersions […]

Jan Fišer, the recipient of the Faculty Prešeren Prize (FMF) in Physics

Award announcement [link] Fakultetne nagrade za študijsko leto 2015/16 Sedem fakultetnih Prešernovih nagrad, nagrada Franca Močnika, 45 Dekanovih priznanj 6. decembra 2016 smo podelili nagrade za najboljše dosežke študentom naše fakultete. Fakultetno Prešernovo nagrado so s področja matematike prejeli Matej Petković, Rok Brence, Blaž Koroša in Petra Poklukar, s področja fizike pa Jan Fišer, Tanja […]

Ultrafast optical spectroscopy of strongly correlated materials and high-temperature superconductors: a non-equilibrium approach, Advances in Physics

In the last two decades, non-equilibrium spectroscopies have evolved from avant-garde studies to crucial tools for expanding our understanding of the physics of strongly correlated materials. The possibility of obtaining simultaneously spectroscopic and temporal information has led to insights that are complementary to (and in several cases beyond) those attainable by studying the matter at […]

Real-time measurement of the emergence of superconducting order in a high-temperature superconductor, Physical Review B

Systems which rapidly evolve through symmetry-breaking transitions on timescales comparable to the fluctuation timescale of the single-particle excitations may behave very differently than under controlled near-ergodic conditions. A real-time investigation with high temporal resolution may reveal insights into the ordering through the transition that are not available in static experiments. We present an investigation of […]

Fast electronic resistance switching involving hidden charge density wave states, Nature Communications

The functionality of computer memory elements is currently based on multi-stability, driven either by locally manipulating the density of electrons in transistors or by switching magnetic or ferroelectric order. Another possibility is switching between metallic and insulating phases by the motion of ions, but their speed is limited by slow nucleation and inhomogeneous percolative growth. […]

Critical femtosecond relaxation dynamics of collective and single-particle excitations through the phase transitions in single crystals of η−Mo4O11, Physical Review B

We present a systematic study of the single-particle and collective excitations by femtosecond transient reflectivity measurements in single crystals η−Mo4O11, investigating the dynamics as a function of temperature with two different pump photon energies (3.1 and 1.55 eV). A remarkable slowing down of the relaxation dynamics is observed at the first charge density wave (CDW) […]

Factors determining large observed increases in power conversion efficiency of P3HT:PCBM solar cells embedded with Mo6S9−xIx nanowires, Synthetic Metals

Power conversion efficiency (PCE) of bulk heterojunction solar cells is influenced by many factors, such as energy level alignment, light trapping and absorption, exciton diffusion, charge carrier mobility and non radiative recombination rate. Despite significant efforts towards improving all these aspects, the PCE remains relatively low and progress has been slow. Here we report a […]

Spontaneous liquid crystal and ferromagnetic ordering of colloidal magnetic nanoplates, Nature Communications

Ferrofluids are familiar as colloidal suspensions of ferromagnetic nanoparticles in aqueous or organic solvents. The dispersed particles are randomly oriented but their moments become aligned if a magnetic field is applied, producing a variety of exotic and useful magnetomechanical effects. A longstanding interest and challenge has been to make such suspensions macroscopically ferromagnetic, that is […]