arXiv subjects

M. O. Safonchik

Publications and source records attributed to M. O. Safonchik.

3 recordsLinked to original sources

arXiv2026

Magnetophonon Resistance Oscillations in Structures with a GaAs Quantum Well and Barriers of AlAs/GaAs$\langleδ$-Si$\rangle$ Superlattices

Magnetophonon resistance oscillations (MPR) associated with the resonant scattering of electrons by optical phonons at temperatures of 77-240 K, as well as resonant scattering of electrons by acoustic phonons (PIRO) at temperatures of 10-25 K, were investigated in the same samples featuring a GaAs quantum well and AlAs/GaAs superlattice barriers doped with Si. The study of MPR demonstrated that resonant electron scattering occurs on bulk longitudinal optical phonons and does not depend on the dimensionality of the system or inter-subband transitions in systems with two subbands of size quantization. However, the amplitude of the oscillation with number $N=1$ in two-dimensional structures depends on the interplay of scattering mechanisms, which, in turn, is influenced by the structure of the system. As for PIRO, in samples with two size quantization subbands, resonant electron scattering by longitudinal acoustic phonons is observed against the background of inter-subband transitions (MISO), leading to their interference.

cond-mat.mes-hall↗

arXiv2022

Superconducting spin valves based on a single spiral magnetic layer

A detailed investigation of a superconducting spin-triplet valve is presented. This spin-valve consists of a superconducting film covering a metal with an intrinsic spiral magnetic order, which could result from competing isotropic exchanges or, if the crystal lattice breaks central symmetry, from asymmetric Dzyaloshinskii-Moriya exchange. Depending on the anisotropy, such a metal may change its magnetization either from a spiral to uniform order, as seen in Ho and Er, or in the direction of the spiral itself, as in crystals of the B20-type structure (such as MnSi, (Fe,Co)Si, FeGe, etc.). The nonuniform magnetic order controls the appearance of long-range triplet superconducting correlations at strong exchange fields, affecting the detailed character of the proximity effect. We show that the magnetic control of the spin-valve behavior can also be obtained from moderately low exchange fields (typically associated to negligible long-range triplet correlations), thanks to an orientation-dependent averaging mechanism of the magnetic inhomogeneity on the scale of the Cooper pairs. Our numerical calculations reveal that the spin-valve effect is in fact magnified at moderately low exchange fields, when the exchange splitting in the spiral magnet is comparable to the superconducting gap, and the spiral period is less than or equal to the superconducting coherence length in the magnet multiplied by $2π$.

cond-mat.supr-con↗

arXiv2002

Magnetophonon resonance in quantum wells in tilted field. What is concealed behind its angular dependence?

Magnetophonon resonance in quantum wells in a tilted magnetic field B is investigated. Measurements of the Hall coefficient and correspondingly of the carrier concentration as a functions of magnetic field and temperature are simultaneously performed. It is shown that the experimental data can be interpreted in terms of a great sensitivity of the effect to the variation of the two dimensional carrier concentration n in a certain concentration interval. In other words, the observed angular dependence of the MPR amplitudes is a manifestation of dependence of n on the magnitude of the magnetic field B.

cond-mat.str-el↗