The effect of inserted NiO layer on spin-Hall magnetoresistance in Pt/NiO/YIG heterostructures

TL;DR

This study explores how inserting an NiO layer in Pt/NiO/YIG heterostructures affects spin-current transport and spin-Hall magnetoresistance, revealing that NiO blocks magnetic proximity effects and influences spin transport depending on temperature.

Contribution

It demonstrates the dual role of NiO in blocking magnetic proximity effects and modulating spin-current transport, providing insights into AFMI's influence on spintronic properties.

Findings

NiO insertion reduces SMR at low temperatures due to AFM order

NiO effectively screens magnetic proximity effects on Pt

NiO facilitates spin current transport between Pt and YIG

Abstract

We investigate the spin-current transport through antiferromagnetic insulator (AFMI) by means of the spin-Hall magnetoressitance (SMR) over a wide temperature range in Pt/NiO/Y$_3$Fe$_5$O$_{12}$ (Pt/NiO/YIG) heterostructures. By inserting the AFMI NiO layer, the SMR dramatically decreases by decreasing the temperature down to the antiferromagnetically ordered state of NiO, which implies that the AFM order prevents rather than promotes the spin-current transport. On the other hand, the magnetic proximity effect (MPE) on induced Pt moments by YIG, which entangles with the spin-Hall effect (SHE) in Pt, can be efficiently screened, and pure SMR can be derived by insertion of NiO. The dual roles of the NiO insertion including efficiently blocking the MPE and transporting the spin current from Pt to YIG are outstanding compared with other antiferromagnetic (AFM) metal or nonmagnetic metal (NM).