arXiv subjects

Evgeny Karashtin

Publications and source records attributed to Evgeny Karashtin.

3 recordsLinked to original sources

arXiv2021

Emission of electromagnetic radiation due to spin-flip transitions in a ferromagnet

We theoretically analyze a possibility of electromagnetic wave emission due to electron transitions between spin subbands in a ferromagnet. Different mechanisms of such spin-flip transitions are cousidered. One mechanism is the electron transitions caused by magnetic field of the wave. Another mechanism is due to Rashba spin-orbit interaction. While two mentioned mechanisms exist in a homogeneously magnetized ferromagnet, there are two other mechanisms that exist in non-collinearly magnetized medium. First mechanism is known and is due to the dependence of exchange interaction constant on the quasimomentum of conduction electrons. Second one exists in any non-collinearly magnetized medium. We study these mechanisms in a non-collinear ferromagnet with helicoidal magnetization distribution. The estimations of probabilities of electron transitions due to different mechanisms are made for realistic parameters, and we compare the mechanisms. We also estimate the radiation power and threshold current in a simple model in which spin is injected into the ferromagnet by a spin-polarized electric current through a tunnel barrier.

cond-mat.mes-hall↗

arXiv2020

Optical responses induced by spin gauge field at the second order

Optical responses of ferromagnetic materials with spin gauge field that drives intrinsic spin curren is theoretically studied. The conductivity tensor is calculated based on a linear response theory to the applied electric field taking account of the non-linear effects of the spin gauge field to the second order. We consider the case where the spin gauge field is uniform, realized for spiral magnetization structure or uniform spin-orbit interaction. The spin gauge field, or an intrinsic spin current, turns out to give rise to anisotropic optical responses, which is expected to be useful to experimental detection of magnetization structures.

cond-mat.mes-hall↗

arXiv2012

Non-reciprocal light diffraction by a vortex magnetic particle

We report a theoretical study of light diffraction by a spherical magnetic particle with a vortex magnetization distribution. It is shown that the intensity of the diffracted light involves a non-reciprocal contribution. This contribution depends on the vorticity of particle magnetization. It appears due to the excitation of an electric quadrupole, magnetic dipole and the addition to the electric dipole moment in the particle, that depend on the particle magnetization vorticity. The estimation of the non-reciprocal contrbution for a cobalt particle and two linear polarizations of the incident light fits the data of recent experimental studies in the lattice of triangle magnetic particles by an order of magnitude.

physics.optics↗