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

• DOI: 10.48550/arxiv.2502.13599
• Publication Date: 2025-01-01
• Authors: Noh, Seunghyeon; Kim, Gye-Hyeon; Lee, Jiyeon; Jung, Hyeonjung; Seo, Uihyeon; So, Gimok; Lee, Jaebyeong; Lee, Seunghyun; Park, Miju; Yang, Seungmin; Oh, Yoon Seok; Jin, Hosub; Sohn, Changhee; Yoo, Jung-Woo
• Keywords: Condensed Matter - Materials Science; Materials Science (cond-mat.mtrl-sci); FOS: Physical sciences

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 Néel 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.