Spin transport in nanowires

TL;DR

This paper investigates high-field spin transport in GaAs nanowires, revealing that one-dimensional channels significantly enhance spin dephasing length and confirming optimal device configuration for spintronic applications.

Contribution

It provides a detailed semiclassical analysis of spin dephasing in GaAs nanowires, highlighting the impact of dimensionality, temperature, and electric field on spin coherence.

Findings

Spin dephasing length in 1D is an order of magnitude higher than in 2D.

Optimal SPINFET configuration aligns ferromagnetic contacts along the channel axis.

Dephasing length is about 22.5 microns at 30K and 10 microns at 77K for 2 kV/cm electric field.

Abstract

We study high-field spin transport of electrons in a quasi one-dimensional channel of a $GaAs$ gate controlled spin interferometer (SPINFET) using a semiclassical formalism (spin density matrix evolution coupled with Boltzmann transport equation). Spin dephasing (or depolarization) is predominantly caused by D'yakonov-Perel' relaxation associated with momentum dependent spin orbit coupling effects that arise due to bulk inversion asymmetry (Dresselhaus spin orbit coupling) and structural inversion asymmetry (Rashba spin orbit coupling). Spin dephasing length in a one dimensional channel has been found to be an order of magnitude higher than that in a two dimensional channel. This study confirms that the ideal configuration for a SPINFET is one where the ferromagnetic source and drain contacts are magnetized along the axis of the channel. The spin dephasing length in this case is about 22.5 microns at lattice temperature of 30K and 10 microns at lattice temperature of 77 K for an electric field of 2 kV/cm. Spin dephasing length has been found to be weakly dependent on the driving electric field and strongly dependent on the lattice temperature.