Spin colossal magnetoresistance in an antiferromagnetic insulator

TL;DR

This paper reports the discovery of spin colossal magnetoresistance (SCMR) in an antiferromagnetic insulator, showing a large, tunable change in spin current near the Ne9el temperature, with potential applications in spintronics.

Contribution

The study introduces the concept of SCMR in an antiferromagnetic insulator and demonstrates its tunability by magnetic field, advancing spintronics device design.

Findings

Observed a two-order magnitude change in spin current near T_N

Demonstrated modulation of spin conductance by magnetic field

Identified SCMR as analogous to colossal magnetoresistance in charge transport

Abstract

Colossal magnetoresistance (CMR) refers to a large change in electrical conductivity induced by a magnetic field in the vicinity of a metal-insulator transition and has inspired extensive studies for decades\cite{Ramirez1997, Tokura2006}. Here we demonstrate an analogous spin effect near the N\'eel temperature $T_{\rm{N}}$=296 K of the antiferromagnetic insulator \CrO. Using a yttrium iron garnet \YIG/\CrO/Pt trilayer, we injected a spin current from the YIG into the \CrO layer, and collected via the inverse spin Hall effect the signal transmitted in the heavy metal Pt. We observed a change by two orders of magnitude in the transmitted spin current within 14 K of the N\'eel temperature. This transition between spin conducting and nonconducting states could be also modulated by a magnetic field in isothermal conditions. This effect, that we term spin colossal magnetoresistance (SCMR), has the potential to simplify the design of fundamental spintronics components, for instance enabling the realization of spin current switches or spin-current based memories.