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| Frustrované kvantové magnety – vplyv jednoosového tlaku | |
| Frustrated quantum magnets – impact of uniaxial pressure | |
| Program: | Mobility |
| Project leader: | doc. RNDr. Gabáni Slavomír, PhD. |
| Duration: | 1.1.2024 – 31.12.2025 |
| Supravodivosť v tenkých filmoch nitridov – materiály pre budúce kvatové zariadenia | |
| Superconductivity in nitride thin films – materials for future quantum devices | |
| Program: | Other |
| Project leader: | RNDr. Pristáš Gabriel, PhD. |
| Annotation: | The main aim of our common project is study superconductivity in nitride thin films. It was shown, that narrow NbN superconducting strips could be used forconstruction of ultrafast single photon detectors, which are expected to play important role in the secure quantum communications. Very recently, team from Montanuniversität Leoben succeeded in preparation of superconducting high entropy alloy (HEA) thin films and team from Slovak side preformed measurements of its superconducting properties. Preparation of nitride HEAs will be next step in effort to improve superconducting parameters of thin films for the purpose to be used in future quantum devices. |
| Duration: | 1.11.2023 – 31.10.2024 |
| EMP – Europská Mikrokelvinová Platforma | |
| European Microkelvin Platform | |
| Program: | Horizon 2020 |
| Project leader: | RNDr. Skyba Peter, DrSc. |
| Project webpage: | https://emplatform.eu/ |
| Duration: | 1.1.2019 – 31.12.2023 |
| TMQM – Ladenie frustrovaných kovových kvantových magnetov | |
| Tuning of frustrated metallic quantum magnets | |
| Program: | Inter-academic agreement |
| Project leader: | doc. RNDr. Gabáni Slavomír, PhD. |
| Duration: | 1.1.2021 – 31.12.2022 |
| Supravodivé vlastnosti tenkých vrstiev boridov | |
| Superconducting properties of boride thin films | |
| Program: | Mobility |
| Project leader: | doc. RNDr. Flachbart Karol, DrSc., akademik US Slovenska |
| Annotation: | The aim of the mobility project is to prepare thin films of superconducting borides YB6 and ZrB12, and to investigate their properties as function of thickness, microstructure and applied pressure.The outcome of this investigation will be new information about how the superconducting properties of bulk (3D) superconductors change when they become two dimensional (2D). In this regard namely a modification of superconducting properties is expected due to a considerable change of rich phonon spectra in borides and of the related electron-phonon interaction, which are responsible for the origin of superconductivity. This research on borides is unexplored, therefore new and original results are expected.The project will, moreover, enable a mutual use of laboratory equipment (for thin film preparation in Leoben, for their investigation in Kosice), it will lead to promotion of post-docs and PhD students, to preparation of common publications, and probably also to further common projects. |
| Duration: | 1.1.2021 – 31.12.2022 |
| TESTIMONIES – Teoretické a experimentálne štúdium nanomateriálov na báze oxyhydridov prechodových kovov pre supravodivosť a fotokatalýzu | |
| Theoretical and Experimental Study of Transition Metal Oxyhydride Nanomaterials for Superconductivity and Photocatalysis | |
| Program: | ERANET |
| Project leader: | doc. RNDr. Flachbart Karol, DrSc., akademik US Slovenska |
| Duration: | 1.10.2019 – 30.9.2022 |
| MGFS – Kovové geometricky frustrované systémy | |
| Metallic geometrically frustrated systems | |
| Program: | Inter-academic agreement |
| Project leader: | doc. RNDr. Gabáni Slavomír, PhD. |
| Annotation: | The principal aim of this project is to establish the microscopic anisotropy parameters and the relevant terms for the magnetic interaction in MGFS. Despite significant experimental and theoretical work, such parameters are unknown for the compounds (e.g. TmB4, HoB4) which form a Shastry Sutherland lattice (SSL) as well as for the highly symmetric face centered cubic (fcc) lattice based systems (e.g. HoB12). The experimental approach will be magnetisation measurements as a function of field direction, neutron diffraction combined with modelling techniques like WIEN2K, McPhase or SpinW. The oscillatory RKKY exchange interaction parameters are expected to be susceptible to applied pressure as well as to alloying. Suitable methods and oriented samples of rare earth borides are available.Crystal field anisotropy is theoretically described by a multipole expansion of theelectric field. The crystal field level splitting parameters will be determined frommagnetisation and specific heat data, as a function of field direction, as well as frominelastic neutron diffraction on powder samples, typically using software like McPhase.The goal of this part is a description of anisotropy of TmB4, HoB4 and the symmetric fcc– counterparts HoB12 and TmB12.The second set of parameters needed for understanding of the Hamiltonian are themagnetic interactions. They will be determined from the dispersion relationsmeasured using neutron spectroscopy on HoB4 and HoB12 along differentcrystallographic directions and in applied magnetic field. These parameters depend ondetails of the RKKY interaction which as a cross check can also be obtained from firstprinciples, using packages like WIEN2K. This type of experiments will be carried out atthe HZB Berlin on isotopically enrich Ho11B4 and Ho11B12 samples, which are availableand first testing experiments were already carried out.We intend to verify results by high pressure experiments (we assume pressuresup to 10 GPa in diamond pressure cells) which is associated with the increase ofitinerant electron concentration in MGFS, and thus with the change of parameters aswell as changes of critical fields and temperatures. This aim will cover MGFS based onthe SSL structure as well as systems based on the fcc structure. Another option to verifyresults is alloying. We will study the effect of substitution of magnetic ions like Tm3+and Ho3+ ions by nonmagnetic Lu3+ ions. Necessary devices and samples for thisresearch are available. |
| Duration: | 1.1.2019 – 31.12.2020 |
| Supravodivosť tenkých filmov boridov | |
| Superconductivity of boride thin films | |
| Program: | Bilateral – other |
| Project leader: | doc. RNDr. Flachbart Karol, DrSc., akademik US Slovenska |
| Annotation: | The aim of the proposed project is to prepare thin films of superconducting high-boron borides(YB6, ZrB12 and LuB12) and investigate their superconducting properties as function ofthickness, microstructure and of applied pressure. The outcome of this investigation will be newknowledge about how superconducting properties of bulk (3D) boride superconductors changewhen they become (quasi) two dimensional (2D). As a result, a variation of superconductingproperties is expected above all due the change of rich boride phonon spectra (and the relatedelectron-phonon interaction) when the structure changes from a 3D one to a 2D one. |
| Duration: | 1.1.2018 – 31.12.2019 |
| CEMENT – Zvýšenie supravodivej Tc v 2D tenkých filmoch vplyvom tlaku | |
| Enhancement of superconducting Tc in 2D thin films under pressure | |
| Program: | JRP |
| Project leader: | RNDr. Pristáš Gabriel, PhD. |
| Duration: | 3.2.2019 – 5.3.2019 |
| Magnetické vlastnosti tetraboridov | |
| Magnetic properties of tetraborides | |
| Program: | Bilateral – other |
| Project leader: | doc. RNDr. Flachbart Karol, DrSc., akademik US Slovenska |
| Duration: | 0.0.0000 – 31.12.2017 |
| ECOM – Neobvyklé chovanie v korelovaných látkach | |
| Emergent behaviour of correlated matter | |
| Program: | COST |
| Project leader: | prof. RNDr. Reiffers Marián, DrSc. |
| Annotation: | no description |
| Project webpage: | http://ecom.tuwien.ac.at/58.0.html, http://www.cost.esf.org/index.php |
| Duration: | 1.1.2005 – 21.9.2009 |
National
| STRIPEX – Vplyv dynamických nábojových pásov na kvantové magnety a supravodiče v extrémnych podmienkach | |
| Influence of dynamic charge stripes on quantum magnets and superconductors in extreme conditions | |
| Program: | SRDA |
| Project leader: | doc. RNDr. Gabáni Slavomír, PhD. |
| Annotation: | The project is aimed at solving the urgent fundamental problem of the genesis of the so-called of dynamic charge stripes (DCS) – inhomogeneous distribution of conduction electron oscillations – and their influence on the properties of strongly correlated electron systems (SCES). The charge stripes play an important role in the high-temperature superconductivity (HTSC) of cuprates and also underlie the mechanisms responsible for the colossal magnetoresistance in manganites, cobaltites, iron-based HTSCs, etc. Observing directly the effect of DCS on the scattering of charge carriers in the mentioned SCES is very sophisticated due to their complex composition, low symmetry of the crystal structure and high sensitivity to external conditions. Instead, it is suitable to use model SCES. Such model materials are rare earth dodecaborides (RB12) with Jahn-Teller structural instability and electronic phase separation on the nanoscale range, in which the appearance of dynamic charge stripes was reliably determined for the first time both for superconductors (ZrB12, LuB12) and for quantum magnets (R = Ho, Er, Tm). The comprehensive study of DCS will be extended by additional model systems based on hexaborides (RB6) and frustrated quantum magnets based on rare earth tetraborides (RB4), and will includes the influence of external extreme conditions such as very low temperatures, high magnetic fields and pressures. |
| Duration: | 1.7.2024 – 30.6.2028 |
| LSD – Nízkorozmerné supravodivé aparáty | |
| Low-dimensional Superconducting Devices | |
| Program: | SRDA |
| Project leader: | Mgr. Szabó Pavol, CSc. |
| Annotation: | Ultralow temperatures have become an important tool for new research avenues in nanoscience, materials research and particularly in quantum nanotechnologies. Scaling down a physical system towards the sizes when the quantum properties surpass classical physics opens a plethora of new quantum-driven effects, thus giving rise to new classes of quantum materials. Within the proposed project we will focus our study on low-dimensional quantum devices, heterostrucures consisting of atomically thin superconducting slabs and aditional layers with different order (inslulator, metal, ferromagnet). In such systems symmetries can be broken possibly allowing for non trivial topological quantum states relevant for future technologies. Atomically thin layered materials are systems with zero limit bulk-to-surface ratio. Their physical properties are strongly affected by interfacing with other systems. Therefore, they represent an accessible platform for the abundance of quantum effects that can be engineered by combining them into vertical stacks using exfoliation techniques. One identifies two types of layered systems – atomically thin artificially prepared van der Waals heterostructures [Science 353, aac9439 (2016)], and naturally layered three-dimensional crystal systems. A special class of naturally layered materials is misfit structures combining alternating atomic layers of hexagonal transition metal dichalcogenides and slabs of ionic rare-earth monochalcogenides in the same superlattice [APL Mater 10, 100901 (2022)]. They feature new state of quantum matter, the Ising superconductivity resulting from broken inversion symmetry and strong spin-orbit coupling as has been recently shown by us. The misfits are also exfoliative and thus incorporable as units in vertical stacks. |
| Duration: | 1.9.2024 – 31.12.2027 |
| Vylepšenie supravodivých parametrov vysoko-entropických zliatin tenkých filmov | |
| Enhancement of superconducting parameters in high-entropy alloy thin films | |
| Program: | VEGA |
| Project leader: | RNDr. Pristáš Gabriel, PhD. |
| Annotation: | Superconducting materials have become an integral part of the latest technologies such as quantum computers,single-photon detectors, magnetic resonance, SQUID, etc. Achieving room-temperature superconductivity is nomore the only goal, but targeted improvement of superconducting parameters (upper critical field, criticaltemperature) for application needs is the key. Extreme conditions in the form of very low temperatures, highpressures and reduction dimensions into quasi-two dimensions are very powerful tools in this endeavor. Inparticular, in case of thin films the superconducting properties can be tuned by several external parameters (e.g.film thickness, substrate, interfaces). The main goal of the project is to improve superconducting parameters ofthe high-entropy alloys and other materials in the form of thin films in purpose for use in future quantumapplications technology. |
| Duration: | 1.1.2024 – 31.12.2027 |
| Magnetická frustrácia a supravodivosť v 2D a 3D boridoch | |
| Magnetic frustration and superconductivity in 2D and 3D borides | |
| Program: | VEGA |
| Project leader: | RNDr. Pristáš Gabriel, PhD. |
| Annotation: | Borides form a wide class of materials with different physical properties. Metallic geometrically frustratedmagnetic tetraborides (REB4) are 2D frustrated systems and together with their fcc 3D counterpartsdodecaborides (REB12) pose an ideal playground for study of 2D/3D interplay of frustration in megnetic systems.Uniaxial pressure, as well as hydrostatic pressure will be the tuning parameters which can change the interactionbetween magnetic moments. Depending on the direction of uniaxial pressure we will be able to change themagnitude of interactions in different crystallographic directions and test theoretical predictions. A similarcrossover between 2D and 3D can be studied also in superconducting borides as YB6, ZrB12 and LuB12. Even ifthere exist at present time a rather good understanding of the physical properties of bulk metallic borides, thereare still serious open questions what will happen if one dimension will be reduced considerably – by preparingthin films of corresponding borides. |
| Duration: | 1.1.2020 – 31.12.2023 |
| ECODISC – Elektrónové korelácie v neusporiadaných supravodičoch | |
| Electron correlations in disordered superconductors | |
| Program: | SRDA |
| Project leader: | Mgr. Szabó Pavol, CSc. |
| Annotation: | Project aims at understanding of the effect of disorder on superconductivity in systems which are close to Superconductor-Insulator Transition as well as in thin films of hydrides. The thin films of MoN, MoC, TiN of various thickness and stoichiometry and on different substrates as well as polycrystalline and nanostructured boron-doped diamond will be prepared. Some of these systems reveal fermionic and some bosonic effects insuperconducting state. By means of conductance measurements from DC to optical frequency range as well as by means of the scanning tunneling microscopy and spectroscopy at very low temperatures and in high magnetic field we will address the question of what kind of superconductivity is established in strongly disorderd systems where already quasiparticles out of superconducting state reveal renormalized density of states around the Fermi energy. We want also to understand the appearence of superconductivity in thin films of hydrides. We will explore the effect of disorder changing upon hydrogen content, thickness of film, substrate, microstructure and applied pressure on superconductivity in YHx, TiHx, VHx hydrides and their oxyhydrides. |
| Duration: | 1.7.2019 – 30.6.2023 |
| MIKROKELVIN – Kvantové materiály pri ultra-nízkych teplotách – MIKROKELVIN | |
| Quantum matters at very low temperatures – MICROKELVIN | |
| Program: | Štrukturálne fondy EÚ Výskum a inovácie |
| Project leader: | RNDr. Skyba Peter, DrSc. |
| Duration: | 1.1.2020 – 30.6.2023 |
| FRUSTKOM – Frustrované kovové magnetické systémy | |
| Frustrated metallic magnetic systems | |
| Program: | SRDA |
| Project leader: | doc. RNDr. Gabáni Slavomír, PhD. |
| Annotation: | The up to now experimental and theoretical studies of frustrated magnetic systems (FMS) has been concentrated mainly on dielectric systems. Such systems can be found in 2D and 3D lattices based on equilateral triangles, and in dielectrics the interaction between their spins can be relatively well defined and described. In metallic FMS (M-FMS), which have been much less studied, an important role plays the long-range indirect exchange interaction between the spins mediated by conduction electrons (the RKKY interaction). To the small number of up to now studied M-FMS belong also some rare earth metallic borides having a fcc (e.g.HoB12, ErB12) or Shastry-Sutherland (e.g.TmB4, HoB4, ErB4) structure. This project aims are to investigate experimentally the impact of high pressure (hydrostatic and uniaxial), the influence of alloying and the anisotropy on the magnetic, transport and thermal properties of M -FMS, which has not been studied yet. A pioneering work will be above all the direct observation of magnetic structures of individual phase diagram regions of these M-FMS by spin-polarized scanning tunnelling microscopy. Investigated will be also the dynamics of magnetic structures (the influence of the rate of change of the magnetic field on these structures) and the study of magnetic excitations (by neutron diffraction methods) in selected tetraborides and dodecaborides.The challenging experimental studies, for which both high quality samples and suitable methods are already available, will be supported by the theoretical interpretation of received results, and by the theoretical elaboration. |
| Project webpage: | http://extremeconditions.saske.sk/projects/ |
| Duration: | 1.8.2018 – 31.12.2022 |
| Vplyv extrémnych podmienok na silne korelované elektrónové systémy. | |
| Influence of extreme conditions on strongly correlated electron systems | |
| Program: | VEGA |
| Project leader: | doc. RNDr. Gabáni Slavomír, PhD. |
| Annotation: | Strong correlations between free (conduction) and bound (localized) electrons in a condensed matter can be change or modified by extreme conditions (very low temperatures, high pressures and magnetic fields), what often leads to the creation of new/exotic states/effects in these materials. In this proposal, we will experimentally study the newest open problems in strongly correlated electron systems (SCES), as surface conductivity in topological Kondo insulators, dynamics of frustrated antiferromagnets, Kondo vs. spin-polaron model in spin glasses, superconductivity under pressure. All this will be a very time-consuming research on new-produced samples. |
| Duration: | 1.1.2016 – 31.12.2019 |
| PSI – Prechod supravodič – izolant | |
| Superconductor – insulator transition | |
| Program: | SRDA |
| Project leader: | Mgr. Szabó Pavol, CSc. |
| Annotation: | The project aims at understanding the problem of how superconductor transforms to insulator at increaseddisorder. The questions of what is the force driving the superconducting transition temperature to lower values inultrathin superconducting films and what is the mechanism of the quantum phase transition betweensuperconducting and insulating states will be addressed experimentally as well as theoretically. Thesuperconducting films of various content with thicknesses down to few atomic layers as well as thenanostructures and resonators on their basis will be prepared. Transport, microwave and optical properties ofthese objects will be investigated. By means of the subkelvin scanning tunnelling microscope the spectral mapsof the quasiparticle density of states at ultralow temperatures and in high magnetic fields will be measured. Wewill explore possibilities to prepare sensitive photon detectors and amplifiers based on ultrathin disorderedsuperconducting films for the spectroscopy in physics, chemistry and biology.Dynamics of the surface states in another macroscopic quantum object, the superfluid 3He which is thetopological insulator at ultra low temperatures, will be investigated experimentally as well as theoretically. Theobjective is to elucidate the dynamics of surface bound excitations in superfluid 3He by means of mechanicalresonators and resolve if the excitations can be identified with the long searched Majorana fermions.By experiment the recent question if samarium hexaboride is a topological insulator will be addressed. |
| Duration: | 1.7.2015 – 30.6.2019 |
| Kvantové fázové prechody. Vplyv chemického a hydrostatického tlaku na vybrané boridy vzácnych zemín. | |
| Quantum phase transitions. Influence of chemical and hydrostatic pressure on selected rare earth borides. | |
| Program: | VEGA |
| Project leader: | doc. RNDr. Gabáni Slavomír, PhD. |
| Annotation: | Quantum phase transitions (QPT) occur at absolute zero temperature, T=0K, when some non-thermal parameterlike external pressure, magnetic field or chemical composition of material is changed, and causes a phasechange. These transitions from one ground state to another are driven by quantum fluctuations. At present, QPTin electronic and magnetic systems have attracted considerable attention thanks to new fundamental discoveriesand explanations of open questions (quantum Hall effect, non-Fermi liquid behavior of electrons, unconventionalsuperconductivity in magnetic materials). In this proposal, we plan to / will study especially the influence of highpressure and chemical composition on mostly magnetic rare earth borides at very low temperatures and inmagnetic fields. There are possibilities to observe the new (quantum) phases of materials and to explain theirphysical properties in the vicinity of so called quantum critical points (QCP) at mentioned extreme conditions(pressures up to 10 GPa, mK temp.). |
| Project webpage: | https://www.e-vega.sav.sk/ |
| Duration: | 1.1.2013 – 31.12.2015 |
| NEMESYS – Nekonvenčné kvantové stavy v nanoskopických magnetických systémoch. | |
| Novel quantum states in nanoscopic magnetic systems. | |
| Program: | SRDA |
| Project leader: | doc. RNDr. Gabáni Slavomír, PhD. |
| Annotation: | The project contributes to the extension of bordes of knowledge in the field of nanoscopic magnetic systems. Specifically, the project focuses on several very actual aspects of nanomagnets such as size effects, influence of the crystal field, dipolar coupling, frustration, Dzyaloshinskii-Moriya interaction etc., on the ground-state and finite-temperature properties of isolated clusters. Another aspect is the investigation of the effect of inter-cluster coupling, which is always present in real materials and leads to the modification of the ground-state and finite-temperature properties of the clusters embedded into extended lattices. This real effect often induces novel cooperative phenomena. The attention is paid to novel relaxation mechanisms due to the coupling of the nanoscopic magnetic systems with other degrees of freedom. The project is also devoted to the influence of preparation methods and deposition techniques on the magnetic properties of the selected nanomagnets. |
| Duration: | 1.7.2012 – 31.12.2015 |
| Supravodiče s nekonvenčným párovaním | |
| Superconductors with non-conventional pairing | |
| Program: | VEGA |
| Project leader: | RNDr. Kačmarčík Jozef, PhD. |
| Annotation: | Since the discovery of high-Tc superconductors a vivid interest is focused on the non-conventional electron pairing mechanisms that could lead to high superconducting critical temperature. Within the proposed project we will study systems where superconductivity comes to play in positive or negative sense with other concurrent order – charge density wave, mainly in dichalcogenides of transition metals. After another surprising discovery – the superconductivity in MgB2 a renewed attention was focused on other non-conventional types of otherwise classical phonon mediated pairing. Within the project we will study other superconducting borides. Clarification of their superconducting mechanism could shed some light on other superconducting clathrates, where a metal ion is trapped in the cage of some other element. We will also work on development of new experimental methods – a compact cooling stage using adiabatic demagnetization and implementation of local magnetometry in 3He cryostat. |
| Duration: | 1.1.2013 – 31.12.2015 |
| Vplyv teploty, magnetického poľa, vysokých tlakov a rozmeru na základný stav zlúčenín s neobvyklým chovaním | |
| The influence of temperature, magnetic fields, high pressure and dimension on the ground state of compounds | |
| Program: | VEGA |
| Project leader: | prof. RNDr. Reiffers Marián, DrSc. |
| Duration: | 1.1.2012 – 31.12.2015 |
| Progresívne materiály s konkurenčnými parametrami usporiadania | |
| Progressive materials with competing order parameters. | |
| Program: | SRDA |
| Project leader: | prof., RNDr. Samuely Peter, DrSc., akademik US Slovenska |
| Annotation: | Phase transitions between different ground states of the material can be induced by altering the balance of competing interactions by changes in composition, pressure, or external applied magnetic field. Interplay between competing orders can lead to new materials with unexpected properties. For example it may stand behind the high temperature superconductivity. Within the project we will focus on fundamental studies in three classes of superconducting materials where the above mentioned competing orders can be put in a play: pnictides, superconductors based on doped semiconductors and dichalcogenides.The project represents a physical realization of the unique experimental basis of the Centre of Cryophysics and Cryonanoelectronics Košice-Bratislava built as a Centre of Excellence of the Slovak R&D agency during last years and supported by the Framework Programme and other projects. |
| Duration: | 1.7.2012 – 30.6.2015 |
| Transportné, tepelné, magnetické a mikrokontaktové vlastnosti základného stavu v korelovaných systémoch pri nízkych teplotách a aplikovaných magnetických poliach | |
| Transport, thermal, magnetic and point-contact properties of ground state in the correlated systems at low temperatures and applied magnetic fields | |
| Program: | VEGA |
| Project leader: | prof. RNDr. Reiffers Marián, DrSc. |
| Duration: | 1.1.2009 – 31.12.2011 |
| ECOM – Neočakávané chovanie korelovanej látky | |
| Emergent behaviour of correlated matter | |
| Program: | Podpora MVTS z prostriedkov SAV |
| Project leader: | prof. RNDr. Reiffers Marián, DrSc. |
| Duration: | 1.1.2005 – 31.12.2009 |
| Neobvyklé chovanie kovových intermetalických zlúčenín pri nízkych teplotách | |
| Emergent behaviour of intermetalic compounds at low temperatures | |
| Program: | VEGA |
| Project leader: | prof. RNDr. Reiffers Marián, DrSc. |
| Duration: | 1.1.2006 – 31.12.2008 |