arXiv subjects

V. Yu. Kachorovskii

Publications and source records attributed to V. Yu. Kachorovskii.

63 records · Page 4Linked to original sources

arXiv2004

Hanle effect driven by weak-localization

The influence of weak localization on Hanle effect in a two-dimensional system with spin-split spectrum is considered. We show that weak localization drastically changes the dependence of stationary spin polarization $\mathbf S$ on external magnetic field $B.$ In particular, the non-analytic dependence of $\mathbf S$ on $\mathbf B$ is predicted for III-V-based quantum wells grown in [110] direction and for [100]-grown quantum wells having equal strengths of Dresselhaus and Bychkov-Rashba spin-orbit coupling. It is shown that in weakly localized regime the components of $\mathbf S$ are discontinuous at $B=0.$ At low $B,$ the magnetic field-induced rotation of the stationary polarization is determined by quantum interference effects. This implies that the Hanle effect in such systems is totally driven by weak localization.

cond-mat.mes-hall↗

arXiv2004

Non-Markovian Effects on the Two-Dimensional Magnetotransport: Low-field Anomaly in Magnetoresistance

We discuss classical magnetotransport in a two-dimensional system with strong scatterers. Even in the limit of very low field, when $ω_c τ\ll 1$ ($ω_c$ is the cyclotron frequency, $τ$ is the scattering time) such a system demonstrates strong negative magnetoresistance caused by non-Markovian memory effects. A regular method for the calculation of non-Markovian corrections to the Drude conductivity is presented. A quantitative theory of the recently discovered anomalous low-field magnetoresistance is developed for the system of two-dimensional electrons scattered by hard disks of radius $a,$ randomly distributed with concentration $n.$ For small magnetic fields the magentoresistance is found to be parabolic and inversely proportional to the gas parameter, $ δρ_{xx}/ρ\sim - (ω_c τ)^2 / n a^2.$ In some interval of magnetic fields the magnetoresistance is shown to be linear $δρ_{xx}/ρ\sim - ω_c τ$ in a good agreement with the experiment and numerical simulations. Magnetoresistance saturates for $ω_c τ\gg na^2$, when the anomalous memory effects are totally destroyed by the magnetic field. We also discuss magnetotransport at very low fields and show that at such fields magnetoresistance is determined by the trajectories having a long Lyapunov region.

cond-mat.mes-hall↗

arXiv2004

Slowing down of spin relaxation in two dimensional systems by quantum interference effects

The effect of weak localization on spin relaxation in a two-dimensional system with a spin-split spectrum is considered. It is shown that the spin relaxation slows down due to the interference of electron waves moving along closed paths in opposite directions. As a result, the averaged electron spin decays at large times as $1/t$. It is found that the spin dynamics can be described by a Boltzmann-type equation, in which the weak localization effects are taken into account as nonlocal-in-time corrections to the collision integral. The corrections are expressed via a spin-dependent return probability. The physical nature of the phenomenon is discussed and it is shown that the "nonbackscattering" contribution to the weak localization plays an essential role. It is also demonstrated that the magnetic field, both transversal and longitudinal, suppresses the power tail in the spin polarization.

cond-mat.mes-hall↗

arXiv2003

Anomalous Negative Magnetoresistance Caused by Non-Markovian Effects

A theory of recently discovered anomalous low-field magnetoresistance is developed for the system of two-dimensional electrons scattered by hard disks of radius $a,$ randomly distributed with concentration $n.$ For small magnetic fields the magentoresistance is found to be parabolic and inversely proportional to the gas parameter, $ δρ_{xx}/ρ\sim - (ω_c τ)^2 / n a^2.$ With increasing field the magnetoresistance becomes linear $δρ_{xx}/ρ\sim - ω_c τ$ in a good agreement with the experiment and numerical simulations.

cond-mat.mes-hall↗

arXiv2002

Electron density stratification in two-dimensional structures tuned by electric field

A new kinetic instability which results in formation of charge density waves is proposed. The instability is of a purely classical nature. A spatial period of arising space-charge and field configuration is inversely proportional to electric field and can be tuned by applied voltage. The instability has no interpretation in the framework of traditional hydrodynamic approach, since it arises from modulation of an electron distribution function both in coordinate and energy spaces. The phenomenon can be observed in thin 2D nanostructures at relatively low electron density.

cond-mat.soft↗

arXiv1999

Level statistics in a two-dimensional system with strong spin-orbit coupling

We study level correlations in a two-dimensional system with a long-range random potential and strong spin-orbit (SO) splitting of the spectrum. The level correlations for sufficiently large splitting are shown to be described by orthogonal Wigner-Dyson statistics, in contrast to the common point of view that a system with the strong SO coupling belongs to the symplectic statistical ensemble. We demonstrate also that in a wide energy interval the level statistics is completely determined by transitions between two branches of the split spectrum. A sharp resonance is obtained in the two-level correlation function at energy equal to the value of SO splitting.

cond-mat.mes-hall↗

arXiv1999

Tunnelling Spectroscopy of Localized States near the Quantum Hall Edge

In the paper we dscuss experimental results of M. Grayson et al. on tunneling $I$-$V$ characteristics of the quantum Hall edge. We suggest a two step tunneling mechanism involving localized electron states near the edge, which might account for discrepancy between the experimental data and the predictions of the chiral Luttinger liquid theory of the quantum Hall edge.

cond-mat.mes-hall↗

arXiv1997

Splitting of Landau levels of a 2D electron due to electron-phonon interactions

We show that in a very strong magnetic field $B$ electron-phonon interaction gives rise to a splitting of Landau levels of a 2D electron into a series of infinitely degenerate sublevels. We provide both qualitative and quantitative description of this phenomenon. The cases of interaction with acoustic and polar optical phonons are considered. The energy distance between nearest sublevels in both cases tends to zero as $B^{-1/2}$ at large $B$.

cond-mat.mes-hall↗

arXiv1997

Nonbackscattering Contribution to the Weak Localization

We show that the enhancement of backscattering responsible for the weak localization is accompanied by reduction of the scattering in other directions. A simple quasiclassical interpretation of this phenomenon is presented in terms of a small change in the effective differential cross-section for a single impurity. The reduction of the scattering at the arbitrary angles leads to the decrease of the quantum correction to the conductivity. Within the diffusion approximation this decrease is small, but it should be taken into account in the case of a relatively strong magnetic field when the diffusion approximation is not valid.

cond-mat.mes-hall↗