Tunneling magnetoresistance in altermagnetic RuO$_2$-based magnetic tunnel junctions

TL;DR

This paper provides experimental evidence of altermagnetic properties in RuO$_2$ through spin-dependent tunneling magnetoresistance, confirming its unique spin-split anisotropic band structure and potential for spintronic applications.

Contribution

It demonstrates the altermagnetic nature of RuO$_2$ by measuring TMR, establishing its relevance for spintronics and clarifying previous doubts about its magnetic ground state.

Findings

RuO$_2$ exhibits spin-dependent TMR.

TMR depends on the N9el vector orientation.

Results confirm the altermagnetic band structure of RuO$_2$.

Abstract

Altermagnets exhibit characteristics akin to antiferromagnets, with spin-split anisotropic bands in momentum space. RuO$_2$ has been considered as a prototype altermagnet; however, recent reports have questioned altermagnetic ground state in this material. In this study, we provide direct experimental evidence of altermagnetic characteristics in RuO$_2$ films by demonstrating spin-dependent tunneling magnetoresistance (TMR) in RuO$_2$-based magnetic tunnel junctions. Our results show the spin-splitted anisotropic band structure of RuO$_2$, with the observed TMR determined by the direction of the N\'eel vector of RuO$_2$. These results reflect the altermagnetic nature of RuO$_2$ and highlight its potential for spintronic applications, leveraging the combined strengths of ferromagnetic and antiferromagnetic systems.