Intrinsic Spin and Orbital Hall Effects from Orbital Texture

TL;DR

This paper theoretically demonstrates that intrinsic spin and orbital Hall effects can originate from orbital texture in centrosymmetric systems, with orbital Hall effect occurring even without spin-orbit coupling and converting into spin Hall effect via SOC.

Contribution

It reveals a new mechanism for intrinsic SHE and OHE based on orbital texture, applicable in centrosymmetric systems, and explores their dependence on SOC strength.

Findings

Orbital Hall effect occurs without spin-orbit coupling.

Spin Hall effect is generated from orbital Hall effect via SOC.

Large spin Hall conductivity comparable to platinum.

Abstract

We show theoretically that both intrinsic spin Hall effect (SHE) and orbital Hall effect (OHE) can arise in centrosymmetric systems through momentum-space orbital texture, which is ubiquitous even in centrosymmetric systems unlike spin texture. OHE occurs even without spin-orbit coupling (SOC) and is converted into SHE through SOC. The resulting spin Hall conductivity is large (comparable to that of Pt) but depends on the SOC strength in a nonmonotonic way. This mechanism is stable against orbital quenching. This work suggests a path for an ongoing search for materials with stronger SHE. It also calls for experimental efforts to probe orbital degrees of freedom in OHE and SHE. Possible ways for experimental detection are briefly discussed.