Analogs of Rashba-Edelstein effect from density functional theory

TL;DR

This study analyzes how crystal symmetry influences the Rashba-Edelstein effect (REE) in materials, identifying classes capable of hosting different REE types through symmetry analysis and first-principles calculations, aiding spintronics device design.

Contribution

It provides a comprehensive symmetry-based classification of materials capable of exhibiting various REE configurations, supported by first-principles calculations.

Findings

Certain crystal symmetries support conventional REE.

Spin texture does not directly determine REE configuration.

Materials can host multiple spin-orbit field types depending on symmetry.

Abstract

Studies of structure-property relationships in spintronics are essential for the design of materials that can fill specific roles in devices. For example, materials with low symmetry allow unconventional configurations of charge-to-spin conversion which can be used to generate efficient spin-orbit torques. Here, we explore the relationship between crystal symmetry and geometry of the Rashba-Edelstein effect (REE) that causes spin accumulation in response to an applied electric current. Based on a symmetry analysis performed for 230 crystallographic space groups, we identify classes of materials that can host conventional or collinear REE. Although transverse spin accumulation is commonly associated with the so-called 'Rashba materials', we show that the presence of specific spin texture does not easily translate to the configuration of REE. More specifically, bulk crystals may simultaneously host different types of spin-orbit fields, depending on the crystallographic point group and the symmetry of the specific $k$-vector, which, averaged over the Brillouin zone, determine the direction and magnitude of the induced spin accumulation. To explore the connection between crystal symmetry, spin texture, and the magnitude of REE, we perform first-principles calculations for representative materials with different symmetries. We believe that our results will be helpful for further computational and experimental studies, as well as the design of spintronics devices.