arXiv subjects

Alexey A. Kovalev

Publications and source records attributed to Alexey A. Kovalev.

78 records · Page 5Linked to original sources

arXiv2007

Aharonov-Casher effect in a two dimensional hole gas with spin-orbit interaction

We study the quantum interference effects induced by the Aharonov-Casher phase in a ring structure in a two-dimensional heavy hole (HH) system with spin-orbit interaction realizable in narrow asymmetric quantum wells. The influence of the spin-orbit interaction strength on the transport is investigated analytically. These analytical results allow us to explain the interference effects as a signature of the Aharonov-Casher Berry phases. Unlike previous studies on the electron two-dimensional Rashba systems, we find that the frequency of conductance modulations as a function of the spin-orbit strength is not constant but increases for larger spin-orbit splittings. In the limit of thin channel rings (width smaller than Fermi wavelength), we find that the spin-orbit splitting can be greatly increased due to quantization in the radial direction. We also study the influence of magnetic field considering both limits of small and large Zeeman splittings.

cond-mat.mes-hall↗

arXiv2007

Boundary spin Hall effect in a two-dimensional semiconductor system with Rashba spin-orbit coupling

We derive boundary conditions for the coupled spin-charge diffusion equations at a transmitting interface between two-dimensional electron systems with different strengths of the Rashba spin-orbit (SO) coupling $α$, and an electric field parallel to the interface. We consider the limit where the spin-diffusion length l_s is long compared to the electron mean free path l, and assume that $α$ changes discontinuously on the scale of l_s. We find that the spin density is also discontinuous on the scale of l_s. In the case where the electron mobility is constant across the interface, this leads to the complete suppression of the expected spin injection from a region with $α\neq0$ into a non-SO region with $α=0$.

cond-mat.mtrl-sci↗

arXiv2007

Perpendicular spin valves with ultra-thin ferromagnetic layers

We address two finite size effects in perpendicular transport through magnetic multilayers. When the magnetic layer thickness in spin valves becomes of the order or smaller than the spin-flip diffusion length, structural asymmetries affect the transport properties. A magnetic layer with thickness approaching the magnetic coherence length becomes transparent for spin currents polarized perpendicular to the magnetization. We use the generalized magnetoelectronic circuit theory to investigate both effects on the angular magnetoresistance (aMR) and spin transfer torque. We analyze recent aMR experiments to determine the spin-flip diffusion length in the ferromagnet as well as the interface spin-mixing conductance and propose a method to measure the ferromagnetic coherence length.

cond-mat.mes-hall↗

arXiv2005

Magnetomechanical Torques in Small Magnetic Cantilevers

We study the dnamics of small magnetic cantilevers, either made from Si covered by a magnetic film or entirely ferromagnetic ones. The magnetomechanical torques are found to cause line splittings in ferromagnetic resonance spectra and magnetization reversal facilitated by mechanical degrees of freedom. We show that the magnetomechanical torques can extend the limits of detecting and exciting motion at the nanoscale. A "nanomotor" described here effectively transforms rf magnetic fields into mechanical oscillations. We furthermore propose to integrate mechanical oscillators into magnetoelectronic devices that make use of current-induced spin-transfer torques. This opens new possibilities for electric transducers of nanomechanical motion.

cond-mat.mes-hall↗

arXiv2004

Nano-mechanical magnetization reversal

The dynamics of the ferromagnetic order parameter in thin magnetic films is strongly affected by the magnetomechanical coupling at certain resonance frequencies. By solving the equation of motion of the coupled mechanical and magnetic degrees of freedom we show that the magnetic-field induced magnetization switching can be strongly accelerated by the lattice and illustrate the possibility of magnetization reversal by mechanical actuation.

cond-mat.other↗

arXiv2003

Magnetovibrational coupling in small cantilevers

A nano-magnetomechanical system consisting of a cantilever and a thin magnetic film is predicted to display magnetovibrational modes, which should enable applications for sensors and actuators. The {}``polaritonic{}'' modes can be detected by line splittings in ferromagnetic resonance spectra.

cond-mat.mes-hall↗