Enhancement of Thermally Injected Spin Current through an Antiferromagnetic Insulator

TL;DR

This study demonstrates that inserting a thin antiferromagnetic insulator layer between YIG and a normal metal significantly enhances thermally injected spin currents, especially near the Ne9el temperature, with results supported by theoretical calculations.

Contribution

It reveals a substantial enhancement of spin current via AF insulators and establishes the linear relationship with spin-mixing conductance, providing new insights into spin transport mechanisms.

Findings

Spin current enhanced up to 10 times with AF layer

Maximum enhancement near Ne9el temperature of AF

Linear scaling of enhancement with spin-mixing conductance

Abstract

We report large enhancement of thermally injected spin current in normal metal (NM)/antiferromagnet(AF)/yttrium iron garnet(YIG), where a thin AF insulating layer of NiO or CoO can enhance spin current from YIG to a NM by up to a factor of 10. The spin current enhancement in NM/AF/YIG, with a pronounced maximum near the N\'eel temperature of the thin AF layer, has been found to scale linearly with the spin-mixing conductance at the NM/YIG interface for NM = 3d, 4d, and 5d metals. Calculations of spin current enhancement and spin mixing conductance are qualitatively consistent with the experimental results.