Electrical Detection of Spin Backflow from an Antiferromagnetic Insulator/Y3Fe5O12 Interface

TL;DR

This paper demonstrates electrical detection of spin backflow in a heterostructure involving an antiferromagnetic insulator and YIG, revealing temperature-dependent spin conductance and spin-flip reflection phenomena.

Contribution

It provides new insights into spin transport across antiferromagnetic insulators interfaced with YIG, highlighting the role of magnons and spin fluctuations in spin Hall magnetoresistance.

Findings

SMR strongly depends on temperature due to antiferromagnetic magnons.

Spin current transmits through NiO and reflects at the NiO/YIG interface.

Inverted SMR observed below a temperature that increases with NiO thickness.

Abstract

Spin Hall magnetoresistance (SMR) has been observed in Pt/NiO/Y3Fe5O12 (YIG) heterostructures with characteristics very different from those in Pt/YIG. We show that the SMR in Pt/NiO/YIG strongly correlates with spin conductance, both sharing very strong temperature dependence due to antiferromagnetic magnons and spin fluctuation. This phenomenon indicates that spin current generated by spin Hall effect in the Pt transmits through the insulating NiO and is reflected from the NiO/YIG interface. Inverted SMR has been observed below a temperature which increases with the NiO thickness, suggesting spin-flip reflection from the antiferromagnetic NiO exchange coupled with the YIG.