Interplay between quantum dissipation and an in-plane magnetic field in the spin ratchet effect

TL;DR

This paper explores how a transverse magnetic field influences the pure spin ratchet effect in a dissipative system with Rashba spin-orbit interaction, showing that magnetic fields can modulate the efficiency of spin current generation.

Contribution

It provides an analytical expression for the spin ratchet current and demonstrates the magnetic field's role in tuning the effect's magnitude.

Findings

Pure spin currents can be generated with unbiased ac driving at low temperatures.

The magnetic field affects the efficiency but not the existence of the spin ratchet effect.

The effect relies on spin-orbit interaction, orbital coupling, and spatial asymmetry.

Abstract

We investigate the existence of the pure spin ratchet effect in a dissipative quasi-one-dimensional system with Rashba spin-orbit interaction. The system is additionally placed into a transverse uniform stationary in-plane magnetic field. It is shown that the effect exists at low temperatures and pure spin currents can be generated by applying an unbiased ac driving to the system. An analytical expression for the ratchet spin current is derived. From this expression it follows that the spin ratchet effect appears as a result of the simultaneous presence of the spin-orbit interaction, coupling between the orbital degrees of freedom and spatial asymmetry. In this paper we consider the case of a broken spatial symmetry by virtue of asymmetric periodic potentials. It turns out that an external magnetic field does not have any impact on the existence of the spin ratchet effect, but it influences its efficiency enhancing or reducing the magnitude of the spin current.