Inverse Orbital Torque via Spin-Orbital Entangled States

TL;DR

This paper provides experimental evidence of inverse orbital torque mediated by spin-orbital entangled states in a YIG/Pt/CuOx structure, revealing new insights into spin-orbital physics and potential orbitronic applications.

Contribution

It demonstrates the reciprocal inverse orbital torque in a YIG/Pt/CuOx system and attributes it to the inverse orbital Rashba-Edelstein effect at the interface, advancing understanding of spin-orbital entanglement.

Findings

Observation of inverse orbital torque in YIG/Pt/CuOx.

Enhanced signal attributed to inverse orbital Rashba-Edelstein effect.

Evidence of spin-orbital entangled states mediating the effect.

Abstract

While current-induced torque by orbital current has been experimentally found in various structures, evidence for its reciprocity has been missing so far. Here, we report experimental evidence of strong inverse orbital torque in YIG/Pt/CuOx (YIG = Y3Fe5O12) mediated by spin-orbital entangled electronic states in Pt. By injecting spin current from YIG to Pt by the spin pumping via ferromagnetic resonance and by the spin Seebeck effect, we find a pronounced inverse spin Hall effect-like signal. While a part of the signal is explained as due to the inverse spin-orbital Hall effect in Pt, we also find substantial increase of the signal in YIG/Pt/CuOx structures compared to the signal in YIG/Pt. We attribute this to the inverse orbital Rashba-Edelstein effect at Pt/CuOx interface mediated by the spin-orbital entangled states in Pt. Our work paves the way toward understanding of spin-orbital entangled physics in nonequilibrium and provides a way for electrical detection of the orbital current in orbitronic device applications.