Neel vector dependent orbital Hall effect in altermagnetic RuO2

TL;DR

This paper theoretically investigates the orbital Hall effect in altermagnetic RuO2, revealing a Neel vector-dependent orbital Hall conductivity and mechanisms involving spin-orbit interaction, with implications for controllable orbital current generation.

Contribution

It introduces a first-principles theoretical analysis of the orbital Hall effect in RuO2, highlighting the dependence on the Neel vector and the underlying mechanisms involving spin-orbit coupling.

Findings

Orbital Hall conductivity depends on the Neel vector orientation.

Spin-orbit interaction converts spin current into orbital current.

Orbital angular momentum is anisotropically recovered under ligand field.

Abstract

Orbital Hall effect in the altermagnetic RuO2 is theoretically investigated. Transport calculations using the Kubo formula with a first-principles tight-binding model present a significant orbital Hall conductivity depending on the direction of the Neel vector. An pertuabative analysis explaines the mechanism by two roles of the spin-orbit interaction: converting the spin current into the parallelly polarized orbital current; recovering the orbital angular momentum anisotropically under the orthorhombic ligand field on the Ru sites. From an application perspective, this effect provides a promising method of generating orbital currents polarizing to arbitrary directions, realising an orbital source offering both controllability and efficiency.