Orbital Edelstein effect of electronic itinerant orbital motion at edges

TL;DR

This paper investigates the orbital Edelstein effect at edges of lattice models, revealing how inter-atomic orbital angular momentum contributes to edge accumulation and its connection to higher-order topological insulators.

Contribution

It introduces the study of inter-atomic OAM contributions to the orbital Edelstein effect at edges, especially in higher-order topological insulators, expanding orbital physics understanding.

Findings

Edge OAM accumulation is driven by electron wiggling motion.

Bulk-boundary correspondence does not hold for OAM accumulation.

Higher-order topological insulators exhibit distinct OAM behaviors.

Abstract

In the study of orbital angular momentum (OAM), the focus has been predominantly on the intra-atomic contribution. However, recent research has begun to shift towards exploring the inter-atomic contribution to OAM dynamics. In this paper, we investigate the orbital Edelstein effect (OEE) arising from the inter-atomic OAM at the edges. We explore the OAM texture within edge states and unveil the OAM accumulation at the edges using several lattice models based on the $s$ orbital. By comparing slabs with differently shaped edges, we not only clarify the role of electron wiggling motion in shaping OAM texture but also highlight the absence of bulk-boundary correspondence in the accumulation process. The topological insulator and higher-order topological insulator models further confirm these findings and provide evidence for the relationship between the higher-order topology and the OEE. Our study advances the comprehension of orbital physics and extends its scope to higher-order topological insulators.