Theoretical investigation of spin-filtering in CrAs / GaAs heterostructures

TL;DR

This study uses theoretical calculations to analyze spin-dependent electronic properties of GaAs/CrAs heterostructures, revealing potential for efficient room-temperature spin-filtering devices without requiring half-metallicity.

Contribution

It provides a detailed theoretical investigation of spin-filtering in GaAs/CrAs heterostructures, highlighting the importance of band alignment and lattice structure for device performance.

Findings

Spin-dependent band alignment influences spin-filtering.

Tetragonal CrAs structure is energetically favorable.

Heterostructures show promise for room-temperature spin-filtering.

Abstract

The electronic structure of bulk fcc GaAs, fcc and tetragonal CrAs, and CrAs/GaAs supercells, computed within LMTO local spin-density functional theory, is used to extract the band alignment (band offset) for the [1,0,0] GaAs/CrAs interface in dependence of the spin orientation. With the lateral lattice constant fixed to the experimental bulk GaAs value, a local energy minimum is found for a tetragonal CrAs unit cell with a slightly ($\approx$ 2%) reduced longitudinal ([1,0,0]) lattice constant. Due to the identified spin-dependent band alignment, half-metallicity of CrAs no longer is a key requirement for spin-filtering. Encouraged by these findings, we study the spin-dependent tunneling current in [1,0,0] GaAs/CrAs/GaAs heterostructures within the non-equilibrium Green's function approach for an effective tight-binding Hamiltonian derived from the LMTO electronic structure. Results indicate that these heterostructures are probable candidates for efficient room-temperature all-semiconductor spin-filtering devices.