A5056652296- Quantum and electron transport phenomena
- Physics of Superconductivity and Magnetism
- Semiconductor materials and devices
- Advancements in Semiconductor Devices and Circuit Design
- Iron-based superconductors research
- Surface and Thin Film Phenomena
- Rare-earth and actinide compounds
- Organic and Molecular Conductors Research
- Semiconductor Quantum Structures and Devices
- High-pressure geophysics and materials
- Magnetic properties of thin films
- Magnetism in coordination complexes
- Quantum, superfluid, helium dynamics
- Superconductivity in MgB2 and Alloys
- Magnetic Field Sensors Techniques
- Topological Materials and Phenomena
- Semiconductor materials and interfaces
- Advanced Condensed Matter Physics
- Theoretical and Computational Physics
- Electronic and Structural Properties of Oxides
- Advanced Chemical Physics Studies
- Corporate Taxation and Avoidance
- Advanced Electrical Measurement Techniques
- Magnetic Properties and Applications
- Superconducting Materials and Applications
P.N. Lebedev Physical Institute of the Russian Academy of Sciences
2015-2024
National Research University Higher School of Economics
2016-2024
Russian Academy of Sciences
2002-2024
Institute of High Temperature Electrochemistry
2021-2024
Moscow Institute of Physics and Technology
2011-2021
Moscow Power Engineering Institute
2021
Rutgers, The State University of New Jersey
2002-2004
Johannes Kepler University of Linz
1997-2002
Technion – Israel Institute of Technology
2001
Institute for High Pressure Physics
1991-1999
We have studied the zero magnetic field resistivity of unique high- mobility two-dimensional electron system in silicon. At very low density (but higher than some sample-dependent critical value, $n_{cr}\sim 10^{11}$ cm$^{-2}$), CONVENTIONAL WEAK LOCALIZATION IS OVERPOWERED BY A SHARP DROP OF RESISTIVITY AN ORDER MAGNITUDE with decreasing temperature below 1--2 K. No further evidence for localization is seen down to at least 20 mK. For $n_s<N_{cr}$, sample insulating. The empirically found...
We have studied the temperature dependence of resistivity, \ensuremath{\rho}, for a two-dimensional electron system in silicon at low densities ${\mathit{n}}_{\mathit{s}}$\ensuremath{\sim}${10}^{11}$ ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}2}$, near metal-insulator transition. The resistivity was empirically found to scale with single parameter ${\mathit{T}}_{0}$, which approaches zero some critical density ${\mathit{n}}_{\mathit{c}}$ and increases as power...
We report on fabrication and characterization of the organic field effect transistors (OFETs) surface single crystals rubrene. The parylene polymer film has been used as gate insulator. At room temperature, these OFETs exhibit p-type conductivity with mobility up to 1 cm^2/Vs on/off ratio ~ 10^4. temperature dependence is discussed.
Pressure-stabilized hydrides are a new rapidly growing class of high-temperature superconductors which is believed to be described within the conventional phonon-mediated mechanism coupling. Here we report synthesis yttrium hexahydride Im3m-YH$_6$ that demonstrates superconducting transition with T$_c$ = 224 K at 166 GPa, much lower than theoretically predicted (>270 K). The measured upper critical magnetic field B$_c$$_2$(0) YH$_6$ was found 116-158 T, 2-2.5 times larger calculated value. A...
We report on the fabrication and characterization of single-crystal organic p-type field-effect transistors (OFETs) with hole mobility mu \~ 8 cm2/Vs, substantially higher than that observed in thin-film OFETs. The devices compare favorably OFETs not only this respect: for is nearly independent gate voltage field effect onset very sharp. Subthreshold slope as small S = 0.85 V/decade has been a insulator capacitance Ci 2 +- 0.2 nF/cm2. This corresponds to intrinsic subthreshold Si SCi at...
The anomalous conducting phase that has been shown to exist in zero field dilute two-dimensional electron systems silicon MOSFETs is driven into a strongly insulating state by magnetic of about 20 kOe applied parallel the plane. data suggest limit T -> 0 suppressed an arbitrarily weak field. We call attention striking similarities field-induced superconductor-insulator transitions.
We studied the Shubnikov-de Haas (SdH) oscillations in high-mobility Si-MOS samples over a wide range of carrier densities n approximately (1-50)x10(11) cm(-2), which includes vicinity apparent metal-insulator transition two dimensions (2D MIT). Using novel technique measuring SdH superimposed and independently controlled parallel perpendicular magnetic fields, we determined spin susceptibility chi(*), effective mass m(*), g(*) factor for mobile electrons. These quantities increase gradually...
The recent discovery of high-temperature superconductivity in single-layer iron selenide has generated significant experimental interest for optimizing the superconducting properties iron-based superconductors through lattice modification. For simulating similar effect by changing chemical composition due to S doping, we investigate high-quality single crystals ${\mathrm{FeSe}}_{1\ensuremath{-}x}{\mathrm{S}}_{x}$ ($x=0$, 0.04, 0.09, and 0.11) using magnetization, resistivity, London...
Polyhydrides are a novel class of superconducting materials with extremely high critical parameters, which is very promising for sensor applications. On the other hand, complete experimental study best so far known superconductor, lanthanum superhydride LaH10 , encounters serious complication because large upper magnetic field HC2 (0), exceeding 120-160 T. It found that partial replacement La atoms by Nd results in significant suppression superconductivity : each at% causes decrease TC 10-11...
We report on a collective low temperature metal-insulator transition which develops in dilute 2D electron system Si at zero magnetic field, below critical carrier density ${\mathit{n}}_{\mathit{s}\mathit{c}}$\ensuremath{\approxeq}${10}^{11}$ ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}2}$. In the insulator phase, dc conduction is thermally activated and exhibits sharp threshold as function of electric field. The state field shows many features attributed to pinned Wigner solid. have also observed...
Over the past six years (2015)(2016)(2017)(2018)(2019)(2020)(2021), many superconducting hydrides with critical temperatures TC up to 250 K, which are currently record highs, have been discovered.Now we can already say that a special field of superconductivity has developed.This is hydride at ultrahigh pressures.For most part, properties superhydrides well described by Migdal-Eliashberg theory strong electronphonon interaction, especially when anharmonicity phonons taken into account.We...
The chemical interaction of Sn with H2 by X-ray diffraction methods at pressures 180-210 GPa is studied. A previously unknown tetrahydride SnH4 a cubic structure (fcc) exhibiting superconducting properties below TC = 72 K obtained; the formation high molecular C2/m-SnH14 superhydride and several lower hydrides, fcc SnH2 , C2-Sn12 H18 also detected. temperature dependence critical current density JC (T) in yields gap 2Δ(0) 21.6 meV 180 GPa. has unusual behavior strong magnetic fields:...
We study the behavior of extended states a two-dimensional electron system in silicon magnetic field, B. Our results show that states, corresponding to centers different Landau levels, merge with lowest state as B --> 0. Using our data, we construct an experimental-based ``disorder vs filling factor'' phase diagram for integer quantum Hall effect (QHE). Generalizing this case fractional QHE, it is consistent recently observed direct transitions between insulator and FQHE at 2/5, 2/7, 2/9.
A novel method invented to measure the minute thermodynamic spin magnetization of dilute two dimensional fermions is applied electrons in a silicon inversion layer. Interplay between ferromagnetic interaction and disorder enhances low temperature susceptibility up 7.5 folds compared with Pauli non-interacting electrons. The peaks vicinity density where transition strong localization takes place. At same density, becomes extremely close that free spins (Curie susceptibility), indicating an...
Charged plasma and Fermi liquid are two distinct states of electronic matter intrinsic to dilute two-dimensional electron systems at elevated low temperatures, respectively. Probing their thermodynamics represents challenge because lack an adequate technique. Here, we report a thermodynamic method measure the entropy per in gated structures. Our technique appears be three orders magnitude superior sensitivity a.c. calorimetry, allowing measurements with only 10(8) electrons. This enables us...
Discovery of superconductivity at megabar (MB) pressures in hydrogen sulfide H3S, then metal polyhydrides, starting with binary, LaH10, etc., and ending ternary ones, including (La, Y)H10, revolutionized the field condensed matter physics. These discoveries strengthen hopes for solution century-old problem creating materials that are superconducting room temperature. In experiments performed over past 5 years MB pressures, addition to synthesis hydrides itself, their physical properties were...
It is shown experimentally that the interaction between electrons strongly influences chemical potential of two-dimensional (2D) electron gas. At sufficiently low temperatures and in high magnetic fields, regions filling factor appear where (i) \ensuremath{\mu} diminishes with increasing carrier density, i.e., thermodynamic density states negative; (ii) derivative \ensuremath{\partial}\ensuremath{\mu}/\ensuremath{\partial}H (H field) considerably higher than maximum value for a...
We report thermodynamic magnetization measurements of two-dimensional electrons in several high-mobility Si metal-oxide-semiconductor field-effect transistors. provide evidence for an easily polarizable electron state a wide density range from insulating to deep into the metallic phase. The temperature and magnetic field dependence is consistent with formation large-spin droplets These melt phase increasing temperature, though they survive up large densities.
A comprehensive study of vortex phases and dynamics is presented for a recently discovered high-temperature superconductor YH6 with Tc(onset) 215 K under pressure 200 GPa. The thermal activation energy (U0) derived within the framework thermally activated flux flow (TAFF) theory. yields power law dependence U0 ∝ Hα on magnetic field possible crossover at around 8-10 T. Furthermore, we have depicted phase transition from vortex-glass to vortex-liquid state according Finally, diagram...