Effect of spin–orbit interaction on circular current: pure spin current phenomena within a ring conductor

Abstract

A net circulating current may appear within a quantum ring under finite bias. We study the characteristic features of the circular current in the presence of Rashba spin–orbit interaction (RSOI). Both charge and spin currents appear within the ring. Whereas when the ring is symmetrically connected to the external leads, we can get a pure spin current at non-zero Fermi-energy. On the other hand, for asymmetric ring-to-leads configuration, at zero Fermi-energy, the spin current vanishes but a pure charge current flows within the ring. Tuning RSOI, we demonstrate a way to control the pure spin current externally. This new perspective of the generation of the pure spin circular current can open a new basis for the highly efficient, low energy cost spintronic devices.

Circular current in a one-dimensional open quantum ring in the presence of magnetic field and spin–orbit interaction

“…Throughout the calculations, we consider the hopping strength within the electrodes to be 2 eV. The inter-atomic spacing (a) is considered to be 1 Å [43]. Throughout the paper the energy is calculated in eV.…”

“…In quantum wells with broken structural inversion symmetry, the inter-facial electric field ξ along the z-direction gives rise to the RSOI coupling (σ × p) z = σ x p y − σ y p x . Therefore when a spin moves in the xy plane, it experiences a spin-dependent Lorentz force due to the effective magnetic field B eff [43,72,73]. This force is proportional to the square of the transverse electric field ξ.…”

“…The effects of external fields on the circular current have been less studied [42]. The concept of spin circular current has been put forward in very recent works [32,43]. In this paper, we investigate the charge and spin circular current conductances and transmission functions in the presence of an external magnetic-field, SOI, and both for an open quantum ring for the first time, to the best of our knowledge.…”