Tunneling Magnetoresistance in Altermagnetic RuO2-Based Magnetic Tunnel Junctions

Abstract

Altermagnets exhibit characteristics akin to antiferromagnets, with spin-split anisotropic bands in momentum space. RuO2 has been considered as a prototype altermagnet; however, recent reports have questioned altermagnetic ground state in this material. In this Letter, we demonstrate spin-dependent tunneling magnetoresistance (TMR) in RuO2-based magnetic tunnel junctions, which suggests the spinsplitted anisotropic band structure of our RuO2 films. The observed TMR is contingent on the direction of the Ne<acute accent>el vector of RuO2 and reverse its sign by the inversion of the Ne<acute accent>el vector. These results reflect the altermagnetic nature of RuO2 and highlight its potential for spintronic applications, leveraging the combined strengths of ferromagnetic and antiferromagnetic systems.