arXiv subjects

Vladimir A. Sablikov

Publications and source records attributed to Vladimir A. Sablikov.

42 records · Page 3Linked to original sources

arXiv2010

Edge states in two-dimensional electron gas with heterogeneous spin-orbit interaction

We show that edge states similar to those known for topological insulators exist in two-dimensional electron system with one-band spectrum in the presence of heterogeneous spin-orbit interaction (SOI). These states appear at boundaries between regions with the SOIs of different kind or between the regions with the SOI and without it. Depending on the system parameters they can appear in an energy range lying both in the forbidden and conduction bands of bulk states. The edge states have chiral spin texture and carry a spin current under the equilibrium. We study also the size quantization of the edge states in a strip structure with two boundaries to find an unusual dependence of the quantization energy on the strip width.

cond-mat.mes-hall↗

arXiv2010

Spin-current quantization in a quantum point contact with spin-orbit interaction

We develop a realistic and analytically tractable model to describe the spin current which arises in a quantum point contact (QPC) with spin-orbit interaction (SOI) upon a small voltage is applied. In the model, the QPC is considered as a saddle point of two-dimensional potential landscape. The SOI acts within a finite region and is absent deep in the reservoirs. The SOI strength is not supposed to be strong. It is shown that the spin polarization appears in the third order of the perturbation theory as a result of definite combinations of electron transitions. They include two intersubband transitions to nearest subbands and one intrasubband transition. The spin current is proportional to the cube of the SOI strength and strongly depends on geometric parameters of the saddle point. The spin is polarized in the plane of the QPC and directed normally to the electron current if the SOI is of Rashba type. As a function of the saddle-point potential (i.e., the height of the QPC barrier), the spin conductance and especially the spin polarization have characteristic features (specifically, peaks) correlated with the charge conductance quantization steps. The peak shape depends on the length of the region where the SOI acts. In QPCs with sharp potential landscape, this picture is distorted by interference processes.

cond-mat.mes-hall↗

arXiv2009

Spin currents in a normal two-dimensional electron gas in contact with a spin-orbit interaction region

Spin effects in a normal two-dimensional (2D) electron gas in lateral contact with a 2D region with spin-orbit interaction are studied. The peculiarity of this system is the presence of spin-dependent scattering of electrons from the interface. This results in an equilibrium edge spin current and nontrivial spin responses to a particle current. We investigate the spatial distribution of the spin currents and spin density under non-equilibrium conditions caused by a ballistic electron current flowing normal or parallel to the interface. The parallel electron current is found to generate the spin density near the interface and to change the edge spin current. The perpendicular electron current changes the edge spin current proportionally to the electron current and produces a bulk spin current penetrating deep into the normal region. This spin current has two components, one of which is directed normal to the interface and polarized parallel to it, and the second is parallel to the interface and is polarized in the plane perpendicular to the contact line. Both spin currents have a high degree of polarization ($\sim 40-60%$).

cond-mat.mes-hall↗

arXiv2009

Spin polarization of electron current through a potential barrier in two-dimensional structures with spin-orbit interaction

We show that an initially unpolarized electron flow acquires spin polarization after passing through a lateral barrier in two-dimensional (2D) system with spin-orbit interaction (SOI) even if the current is directed normally to the barrier. The generated spin current depends on the distance from the barrier. It oscillates with the distance in the vicinity of the barrier and asymptotically reaches a constant value. The most efficient generation of the spin current (with polarization above 50%) occurs, when the Fermi energy is near the potential barrier maximum. Since the spin current in SOI medium is not unambiguously defined we propose to pass this current from the SOI region into a contacting region without SOI and show, that the spin polarization loss under such transmission can be negligible.

cond-mat.mes-hall↗

arXiv2008

Equilibrium edge spin currents in two-dimensional electron systems with spin-orbit interaction

We find a specific mechanism of background spin currents in two-dimensional electron systems with spatially nonuniform spin-orbit interaction (SOI) at thermodynamic equilibrium, in particular, in the systems consisting of regions with and without SOI. The spin density flows tangentially to the boundary in the normal and SOI regions within a layer of the width determined by the SOI strength. The density of these edge currents significantly exceeds the bulk spin current density. The spin current is polarized normally to the boundary. The spatial distribution of equilibrium spin currents is investigated in detail in the case of a step-like variation of the SOI strength and potential at the interface.

cond-mat.mes-hall↗

arXiv2007

Evanescent states in 2D electron systems with spin-orbit interaction and spin-dependent transmission through a barrier

We find that the total spectrum of electron states in a bounded 2D electron gas with spin-orbit interaction contains two types of evanescent states lying in different energy ranges. The first-type states fill in a gap, which opens in the band of propagating spin-splitted states if tangential momentum is nonzero. They are described by a pure imaginary wavevector. The states of second type lie in the forbidden band. They are described by a complex wavevector. These states give rise to unusual features of the electron transmission through a lateral potential barrier with spin-orbit interaction, such as an oscillatory dependence of the tunneling coefficient on the barrier width and electron energy. But of most interest is the spin polarization of an unpolarized incident electron flow. Particularly, the transmitted electron current acquires spin polarization even if the distribution function of incident electrons is symmetric with respect to the transverse momentum. The polarization efficiency is an oscillatory function of the barrier width. Spin filtering is most effective, if the Fermi energy is close to the barrier height.

cond-mat.mes-hall↗