Modern Approach to Orbital Hall Effect Based on Wannier Picture of Solids

TL;DR

This paper introduces a Wannier-based method to accurately compute orbital Hall conductivity, capturing both local and non-local contributions, and demonstrates its effectiveness through first-principles calculations on various materials.

Contribution

A novel Wannier function approach based on the modern theory of orbital magnetization that improves the calculation of orbital angular momentum contributions to the orbital Hall effect.

Findings

Significant non-local corrections to OHC compared to traditional approximations.

The new method captures both local and itinerant contributions to OHC.

Enhanced understanding of orbital angular momentum in complex materials.

Abstract

In the field of orbital dynamics and orbital transport, a particularly important quantity is the so-called orbital Hall conductivity (OHC), which is expressed in terms of operators of velocity and orbital angular momentum (OAM). To overcome the difficulties in treating the unbounded position operator, very often atom-centered approximations are used, which capture only a part of the local contributions to the OAM operator. Here, we promote a new approach to quantify the OAM operator in the basis of Wannier functions, which is based on the modern theory of orbital magnetization and which captures both local and itinerant contributions to the OHC. By performing first-principles calculations for various materials, we show that significant corrections to the OHC by non-local effects arise when compared to common approximations. Our approach improves the understanding of the OAM in solids and allows for a precise estimation of various orbital effects in complex materials.