Current-induced spin and orbital polarization in the ferroelectric Rashba semiconductor GeTe

TL;DR

This study explores how electric currents induce spin and orbital polarization in ferroelectric GeTe, revealing that orbital effects dominate and are largely independent of spin-orbit coupling, offering new insights for spintronics.

Contribution

It provides a detailed analysis of current-induced orbital and spin magnetization in GeTe, emphasizing the dominance of the orbital Edelstein effect and its independence from spin-orbit coupling.

Findings

Orbital Edelstein effect surpasses spin Edelstein effect in GeTe.

Orbital magnetization remains robust without spin-orbit coupling.

Fermi surface textures show dominant orbital moments over spin moments.

Abstract

The Edelstein effect is a promising mechanism for generating spin and orbital polarization from charge currents in systems without inversion symmetry. In ferroelectric materials, such as Germanium Telluride (GeTe), the combination of bulk Rashba splitting and voltage-controlled ferroelectric polarization provides a pathway for electrical control of the sign of the charge-spin conversion. In this work, we investigate current-induced spin and orbital magnetization in bulk GeTe using Wannier-based tight-binding models derived from \textit{ab initio} calculations and semiclassical Boltzmann theory. Employing the modern theory of orbital magnetization, we demonstrate that the orbital Edelstein effect entirely dominates its spin counterpart. This difference is visualized through the spin and orbital textures at the Fermi surfaces, where the orbital moment surpasses the spin moment by one order of magnitude. Moreover, the orbital Edelstein effect remains largely unaffected in the absence of spin-orbit coupling, highlighting its distinct physical origin compared to the spin Edelstein effect.