Journal Article

Current-induced spin polarisation in Rashba–Dresselhaus systems under different point groups

Saha, Kush, Dey, Akash, Nandy, Ashis K

2025

Overview

Non-magnetic materials without inversion symmetry typically exhibit strong Rashba spin–orbit coupling (SOC), enabling the well-known Rashba Edelstein effect where an external electrical current induces transverse spin polarisation. In this study, we demonstrate that electrically induced spin polarisation in non-magnetic materials, for example, electronic systems within quantum-well geometries, can significantly be influenced by the system’s point-group symmetries, such as C n and C nv . These symmetries allow various linear and higher-order momentum, k − varying SOC Hamiltonian. Specifically, we show that surfaces having C n point-group symmetry, which permits specific linear and cubic Rashba and Dresselhaus SOC terms, can lead to both orthogonal and non-orthogonal spin polarisations with respect to the applied field. In contrast, surfaces with C nv symmetry exhibit only transverse spin polarisation, regardless of the linear and cubic SOC terms. We further find contrasting spin polarisation for cubic-in- k SOC as compared to the linear-in- k SOC when energy is varied, for example, through doping. Additionally, we show that the surfaces with C n symmetry may exhibit persistent spin current, depending on the relative strength between different momentum-dependent SOC terms. Our finding emphasizes the significance of crystal symmetry in understanding and manipulating induced spin polarisation in noncentrosymmetric materials, especially in surface/interface systems.

• Publisher: IOP Publishing
• Subject: 2D electron gas / Edelstein effect / Electric currents / Electron spin / Electronic systems / Hamiltonian functions / Magnetic materials / Momentum / persistent spin texture / Polarization (spin alignment) / Quantum wells / Rashba and Dresselhaus spin–orbit coupling / Spin-orbit interactions / Spintronics / Symmetry