A5014983247- Physics of Superconductivity and Magnetism
- Iron-based superconductors research
- Superconductivity in MgB2 and Alloys
- Rare-earth and actinide compounds
- Surface and Thin Film Phenomena
- Magnetic and transport properties of perovskites and related materials
- Advanced Condensed Matter Physics
- Magnetic Properties of Alloys
- Thermal Expansion and Ionic Conductivity
- Quantum and electron transport phenomena
- Diamond and Carbon-based Materials Research
- Electronic and Structural Properties of Oxides
- 2D Materials and Applications
- Organic and Molecular Conductors Research
- Graphene research and applications
- Heusler alloys: electronic and magnetic properties
- Topological Materials and Phenomena
- Molecular Junctions and Nanostructures
- High-pressure geophysics and materials
- Magnetic properties of thin films
- Advanced Chemical Physics Studies
- Inorganic Chemistry and Materials
- Theoretical and Computational Physics
- Crystal Structures and Properties
- High Entropy Alloys Studies
Institute of Experimental Physics of the Slovak Academy of Sciences
2015-2024
Slovak Academy of Sciences
2015-2024
University of Pavol Jozef Šafárik
2017-2023
University of Dunaújváros
2020
Institute of Physics of the Slovak Academy of Sciences
2015
Comenius University Bratislava
2015
Temper (United States)
2004
B. Verkin Institute for Low Temperature Physics and Engineering of the National Academy of Sciences of Ukraine
2004
Centre National de la Recherche Scientifique
1997-2002
Université Joseph Fourier
2002
Experimental support is found for the multiband model of superconductivity in recently discovered system MgB(2) with transition temperature T(c) = 39 K. By means Andreev reflection, evidence obtained two distinct superconducting energy gaps. The sizes gaps ( Delta(S) 2.8 meV and Delta(L) 7 meV) are, respectively, smaller larger than expected weak coupling value. Because smearing spectra are hardly distinguishable at elevated temperatures, but when a magnetic field applied presence can be...
We report on specific heat, high magnetic field transport and $ac-$susceptibility measurements magnesium diboride single crystals. The upper critical $H_{c2}$ for fields perpendicular parallel to the Mg B planes is presented first time in entire temperature range. A very different dependence has been observed two directions which yields a dependent anisotropy with $\Gamma \sim$ 5 at low temperatures about 2 near $T_c$. peak effect susceptibility $H \sim $2 T $c-$axis current density presnts...
Directional point-contact Andreev-reflection spectroscopy measurements on the ${\text{Ba}}_{0.55}{\text{K}}_{0.45}{\text{Fe}}_{2}{\text{As}}_{2}$ single crystals are presented. The spectra show significant differences when measured in $ab$ plane comparison with those $c$ direction of crystal. In latter case only a reduced conductance around zero bias has been revealed persisting well above ${T}_{c}$ and probably related to structural magnetic transitions system. Within two superconducting...
The temperature dependence of the upper (${H}_{c2}$) and lower (${H}_{c1}$) critical fields has been deduced from Hall probe magnetization measurements high quality ${\mathrm{M}\mathrm{g}\mathrm{B}}_{2}$ single crystals along two main crystallographic directions. We show that ${\ensuremath{\Gamma}}_{{H}_{c2}}={H}_{c2\ensuremath{\parallel}ab}/{H}_{c2\ensuremath{\parallel}c}$ ${\ensuremath{\Gamma}}_{{H}_{c1}}={H}_{c1\ensuremath{\parallel}c}/{H}_{c1\ensuremath{\parallel}ab}$ differ...
Systematic studies of the NdFeAsOF superconducting energy gap using point-contact Andreev-reflection (PCAR) spectroscopy are presented. At low temperatures PCAR conductance spectra show a pair gap-like peaks at about ± (4–7) mV and in most cases also humps around 10 mV. Fits to s-wave two-gap model allowed determine two gaps system. However, energy-gap features disappear T* = 15–20 K, much below particular Tc junction under study. zero-bias (ZBC) peak emerges, which higher usually overwhelms...
The $\ensuremath{\beta}\text{\ensuremath{-}}\mathrm{B}{\mathrm{i}}_{2}\mathrm{Pd}$ compound has been proposed as another example of a multigap superconductor [Imai et al., J. Phys. Soc. Jpn. 81, 113708 (2012)]. Here, we report on measurements several important physical quantities capable showing presence multiple energy gaps our superconducting single crystals with the critical temperature ${T}_{c}$ close to 5 K. calorimetric study via sensitive ac technique shows sharp anomaly at...
Allotropes of carbon are promising materials for the next generation electronics. In particular, boron-doped synthetic diamond, which is typically highly disordered, provides a powerful stage studying superconductivity in three-dimensional granular system. The authors find that, even deep metallic regime, heavily doped diamond still shows pronounced quantum effects its transport properties, needs to be accounted for---and could exploited---in diamond-based SQUIDs and nanodevices.
We use sub-Kelvin scanning tunneling spectroscopy to investigate the suppression of superconductivity in homogeneously disordered ultrathin MoC films. observe that superconducting state remains spatially homogeneous even on films 3 nm thickness. The vortex imaging suggests global phase coherence our Upon decreasing thickness, when transition drops from 8.5 1.2 K, energy gap follows perfectly Tc. All this is pointing a two-stage fermionic scenario superconductor-insulator (SIT) via metallic...
Cylindrical nanowires made of Co2FeSn Heusler alloy with high spin polarization have been synthetized via template-assisted electrochemical deposition in nanoporous anodic alumina membranes. Their microstructure and morphology characterized by situ studies X-ray diffraction, together scanning transmission electron microscopy techniques. The basic structural magnetic characterization revealed a B2-type cubic ordered structure lattice parameter around 5.8 Å the [110] direction, preferably...
We have prepared and investigated superconducting ${\mathrm{Nb}}_{67}{\mathrm{Hf}}_{11}{\mathrm{Ti}}_{11}{\mathrm{Zr}}_{11}$ ${\mathrm{Nb}}_{35}{\mathrm{Ta}}_{35}{\mathrm{Hf}}_{10}{\mathrm{Ti}}_{10}{\mathrm{Zr}}_{10}$ medium- high-entropy alloys in form of thin films with thicknesses 600, 100, 30 nm, compared their properties bulk counterparts. show that the transition temperature ${T}_{c}$ as well upper critical magnetic field ${B}_{c2}(0)$ decrease decreasing thickness. Application...
Point-contact measurements on the carbon-substituted $\mathrm{Mg}{({\mathrm{B}}_{1\ensuremath{-}x}{\mathrm{C}}_{x})}_{2}$ filament/powder samples directly reveal a retention of two superconducting energy gaps in whole doping range from $x=0$ to $x\ensuremath{\approx}0.1$. The large gap $\ensuremath{\sigma}$-band is decreased an essentially linear fashion with increasing carbon concentrations. changes small ${\ensuremath{\Delta}}_{\ensuremath{\pi}}$ up 3.8% $\mathrm{C}$ are proportionally...
The two-band and/or two-gap superconductivity in aluminum- and carbon-doped $\mathrm{Mg}{\mathrm{B}}_{2}$ has been addressed by the point-contact spectroscopy. Two gaps are preserved all samples with ${T}_{c}^{\ensuremath{'}}s$ down to $22\phantom{\rule{0.3em}{0ex}}\mathrm{K}$. evolution of two as a function critical temperature doped systems suggests dominance band-filling effects, but for increased Al doping, enhanced interband scattering must also be considered. extraction zero-energy...
Superconductivity and ferromagnetism are two mutually antagonistic states in condensed matter. Research on the interplay between these competing orderings sheds light not only cause of various quantum phenomena strongly correlated systems but also general mechanism superconductivity. Here we report observation electronic entanglement superconducting ferromagnetic hydrogenated boron-doped nanodiamond films, which have a transition temperature Tc ∼ 3 K Curie TCurie > 400 K. In spite high...
Extreme in-plane upper critical magnetic fields $B_{c2//ab}$ strongly violating the Pauli paramagnetic limit have been observed in misfit layer $(LaSe)_{1.14}(NbSe_2)$ and $(LaSe)_{1.14}(NbSe_2)_2$ single crystals with $T_c$ = 1.23 K 5.7 K, respectively. The show a two-dimensional to three-dimensional transition at temperatures slightly below an upturn temperature dependence of $B_{c2//ab}$, dependent huge superconducting anisotropy cusplike behavior angular $B_{c2}$. Both misfits are...
The Andreev reflection measurements of the superconducting energy gap in carbon-substituted ${\mathrm{MgB}}_{2}$ are presented. Despite strong suppression transition temperature by 17 K comparison with pure ${\mathrm{MgB}}_{2},$ same reduced value small $2\ensuremath{\Delta}{/kT}_{c}\ensuremath{\approx}1.7$ has been systematically observed. This indicates that two-band/two-gap superconductivity is still preserved here.
The lower $({H}_{c1})$ and upper $({H}_{c2})$ critical fields of ${\mathrm{Mg}}_{1\ensuremath{-}x}{\mathrm{Al}}_{x}{\mathrm{B}}_{2}$ single crystals (for $x=0$, $0.1$, $\ensuremath{\gtrsim}0.2$) have been deduced from local magnetization specific heat measurements, respectively. We show that ${H}_{c1}$ ${H}_{c2}$ are both decreasing with increasing doping content. corresponding anisotropy parameter ${\ensuremath{\Gamma}}_{{H}_{c2}}(0)={H}_{c2}^{ab}(0)∕{H}_{c2}^{c}(0)$ value also decreases...
We present heat capacity measurements on a series of superconducting Cu${}_{x}$TiSe${}_{2}$ single crystals with different Cu content down to 600 mK and up 1 T performed by ac microcalorimetry. The samples cover large portion the phase diagram from an underdoped slightly overdoped region increasing critical temperature charge density wave (CDW) order gradually suppressed. electronic as function normalized $T/{T}_{c}$ shows no difference regardless concentration copper, i.e., how much CDW is...
We investigate the complex conductivity of a highly disordered MoC superconducting film with ${k}_{F}l\ensuremath{\approx}1$, where ${k}_{F}$ is Fermi wave number and $l$ mean free path, derived from experimental transmission characteristics coplanar waveguide resonators in wide temperature range below transition ${T}_{c}$. find that original Mattis-Bardeen model finite quasiparticle lifetime, $\ensuremath{\tau}$, offers perfect description experimentally observed conductivity. show...
We present a detailed characterization of the vortex-glass transition in cubic $(\mathrm{K},\mathrm{B}\mathrm{a}){\mathrm{BiO}}_{3}$ superconductor (with critical temperature ${T}_{c}\ensuremath{\sim}30\mathrm{K}).$ Combining transport measurements down to $0.3\mathrm{K}$ and third-harmonic susceptibility close ${T}_{c}$ we show that field can be well fitted by power law: ${H}_{g}\ensuremath{\sim}(1\ensuremath{-}{T/T}_{c}{)}^{n}$ with $n\ensuremath{\sim}1.5$ over three magnetic decades. In...
In the presence of disorder, superconductivity exhibits short-range characteristics linked to localized Cooper pairs which are responsible for anomalous phase transitions and emergence quantum states such as bosonic insulating state. Complementary well-studied homogeneously disordered superconductors, superconductor-normal hybrid arrays provide tunable realizations degree granular disorder studying transitions. Here, we investigate superconductor–bosonic dirty metal transition in nanodiamond...