Orbital Hall Effect and Angular Momentum Dynamics in Confined Geometries

TL;DR

This paper analyzes the orbital Hall effect in confined geometries, deriving formulas for orbital angular momentum accumulation and exploring its dependence on scattering, revealing new transport behaviors in inhomogeneous systems.

Contribution

It introduces a formula linking orbital angular momentum accumulation to band structure and scattering, and uncovers new OHE contributions in inhomogeneous electric fields.

Findings

OAM decay rate scales with scattering rate inversely

Edge OAM accumulation depends on band parameters

Non-Ohmic flows contribute to OHE beyond intrinsic/extrinsic mechanisms

Abstract

We present an analysis of the orbital Hall effect (OHE) in a strip geometry and derive a formula for the orbital angular momentum (OAM) accumulation at the edges. The result is expressed in terms of band structure parameters and scattering rates, providing a link between experimental observations of the OHE and the underlying microscopics. A key result is that the effective OAM decay rate follows a Dykonov-Perel-like scaling and is inversely proportional to the electron scattering rate, even if the latter is small. Furthermore, investigating OAM transport in an inhomogeneous setting, we show that non-Ohmic flows and spatially varying electric fields result in contributions to the OHE which are distinct from the well known intrinsic and extrinsic mechanisms.