arXiv subjects

V. Pudalov

Publications and source records attributed to V. Pudalov.

3 recordsLinked to original sources

arXiv2018

High-pressure effects on isotropic superconductivity in the iron-free layered pnictide superconductor BaPd2As2

While the layered 122 iron arsenide superconductors are highly anisotropic, unconventional, and exhibit several forms of electronic orders that coexist or compete with superconductivity in different regions of their phase diagrams, we find in the absence of iron in the structure that the superconducting characteristics of the end member BaPd2As2 are surprisingly conventional. Here we report on complementary measurements of specific heat, magnetic susceptibility, resistivity measurements, Andreev spectroscopy, and synchrotron high pressure x-ray diffraction measurements supplemented with theoretical calculations for BaPd2As2. Its superconducting properties are completely isotropic as demonstrated by the critical fields, which do not depend on the direction of the applied field. Under the application of high pressure, Tc is linearly suppressed, which is the typical behavior of classical phonon-mediated superconductors with some additional effect of a pressure-induced decrease in the electronic density of states and the electron-phonon coupling parameters. Structural changes in the layered BaPd2As2 have been studied by means of angle-dispersive diffraction in a diamond-anvil cell. At 12 GPa and 24.2 GPa we observed pressure induced lattice distortions manifesting as the discontinuity and, hence discontinuity in the Birch-Murnaghan equation of state. The bulk modulus is B0=40(6) GPa below 12 GPa and B0=142(3) GPa below 27.2 GPa.

cond-mat.supr-con↗

arXiv2003

The thermodynamic spin magnetization of strongly correlated 2d electrons in a silicon inversion layer

A novel method invented to measure the minute thermodynamic spin magnetization of dilute two dimensional fermions is applied to electrons in a silicon inversion layer. Interplay between the ferromagnetic interaction and disorder enhances the low temperature susceptibility up to 7.5 folds compared with the Pauli susceptibility of non-interacting electrons. The magnetization peaks in the vicinity of the density where transition to strong localization takes place. At the same density, the susceptibility becomes extremely close to that of free spins (Curie susceptibility), indicating an almost perfect compensation of the kinetic energy toll associated with spin polarization by the energy gained from the ferromagnetic correlation. Yet, the balance favors a paramagnetic phase over spontaneous magnetization.

cond-mat.mes-hall↗

arXiv2001

On the Cooling of Electrons in a Silicon Inversion Layer

The cooling of two-dimensional electrons in silicon-metal-oxide semiconductor field effect transistors is studied experimentally. Cooling to the lattice is found to be more effective than expected from the bulk electron-phonon coupling in silicon. Unexpectedly, the extracted heat transfer rate to phonons at low temperatures depends cubically on electron temperature, suggesting that piezoelectric coupling (absent in bulk silicon) dominates over deformation potential. According to our findings, at 100 mK, electrons farther than 0.1 mm from the contacts are mostly cooled by phonons. Using long devices and low excitation voltage we measure electron resistivity down to 100 mK and find that some of the "metallic" curves, reported earlier, turn insulating below about 300 mK. This finding renders the definition of the claimed 2D metal-insulator transition questionable. Previous low temperature measurements in silicon devices are analyzed and thumb rules for evaluating their electron temperatures are provided.

cond-mat.mes-hall↗