Non-reciprocity in magnon mediated charge-spin-orbital current interconversion

TL;DR

This paper demonstrates nonreciprocal magnon-mediated charge-spin-orbital current conversion in magnetic systems with heavy-metal nanowires, showing that orbital effects can break reciprocity and enhance efficiency.

Contribution

It reveals how orbital Hall effect introduces nonreciprocity in magnon-mediated angular momentum transport, a novel insight in spintronics.

Findings

Magnon polarization via combined SHE and OHE is 35% more efficient than the reverse process.

Nonreciprocity arises from spin vorticity caused by electron drift velocity differences.

Orbital transport mechanisms significantly influence angular momentum transfer efficiency.

Abstract

In magnetic systems, angular momentum is carried by spin and orbital degrees of freedom. Nonlocal devices, comprising heavy-metal nanowires on magnetic insulators like yttrium iron garnet (YIG), enable angular momentum transport via magnons. These magnons are polarized by spin accumulation at the interface through the spin Hall effect (SHE) and detected via the inverse SHE (iSHE). The processes are generally reciprocal, as demonstrated by comparable efficiencies when reversing injector and detector roles. However, introducing Ru, which enables the orbital Hall effect (OHE), disrupts this reciprocity. In our system, magnons polarized through combined SHE and OHE and detected via iSHE are 35% more efficient than the reverse process. We attribute this nonreciprocity to nonzero spin vorticity, resulting from varying electron drift velocities across the Pt/Ru interface. This study highlights the potential of orbital transport mechanisms in influencing angular momentum transport and efficiency in nonlocal spintronic devices.