Effects of filling, strain, and electric field on the N\'{e}el vector in antiferromagnetic CrSb

TL;DR

This study uses density functional theory to explore how strain, electric fields, and band filling influence the magnetic anisotropy and Néel vector in bulk and thin-film CrSb, revealing mechanisms for magnetic control in antiferromagnetic spintronics.

Contribution

It provides a detailed analysis of how strain, electric field, and band filling affect the magnetic anisotropy energy and NéeL vector in CrSb, highlighting voltage-controlled magnetic anisotropy effects.

Findings

MAE of bulk CrSb is 1.2 meV per unit cell.

Thin films exhibit broken inversion symmetry and become ferrimagnetic.

Strain can switch the sign of MAE, enabling magnetic control.

Abstract

CrSb is a layered antiferromagnet (AFM) with perpendicular magnetic anisotropy, a high N\'{e}el temperature, and large spin-orbit coupling (SOC), which makes it interesting for AFM spintronic applications. To elucidate the various mechanisms of N\'{e}el vector control, the effects of strain, band filling, and electric field on the magnetic anisotropy energy (MAE) of bulk and thin-film CrSb are determined and analysed using density functional theory. The MAE of the bulk crystal is large (1.2 meV per unit cell). Due to the significant ionic nature of the Cr-Sb bond, finite slabs are strongly affected by end termination. Truncation of the bulk crystal to a thin film with one surface terminated with Cr and the other surface terminated with Sb breaks inversion symmetry, creates a large charge dipole and average electric field across the film, and breaks spin degeneracy, such that the thin film becomes a ferrimagnet. The MAE is reduced such that its sign can be switched with realistic strain, and the large SOC gives rise to an intrinsic voltage controlled magnetic anisotropy (VCMA). A slab terminated on both faces with Cr remains a compensated AFM, but with the compensation occurring nonlocally between mirror symmetric Cr pairs. In-plane alignment of the moments is preferred, the magnitude of the MAE remains large, similar to that of the bulk, and it is relatively insensitive to filling.