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arXiv · 2409.13504

Absence of altermagnetic spin splitting character in rutile oxide RuO$_2$

Jiayu Liu·Jie Zhan·Tongrui Li·Jishan Liu·Shufan Cheng·Yuming Shi·Liwei Deng·Meng Zhang·Chihao Li·Jianyang Ding·Qi Jiang·Mao Ye·Zhengtai Liu·Zhicheng Jiang·Siyu Wang·Qian Li·Yanwu Xie·Yilin Wang·Shan Qiao·Jinsheng Wen·Yan Sun·Dawei Shen
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Abstract

Rutile RuO$_2$ has been posited as a potential $d$-wave altermagnetism candidate, with a predicted significant spin splitting up to 1.4 eV. Despite accumulating theoretical predictions and transport measurements, direct spectroscopic observation of spin splitting has remained elusive. Here, we employ spin- and angle-resolved photoemission spectroscopy to investigate the band structures and spin polarization of thin-film and single-crystal RuO$_2$. Contrary to expectations of altermagnetism, our analysis indicates that RuO$_2$'s electronic structure aligns with those predicted under non-magnetic conditions, exhibiting no evidence of the hypothesized spin splitting. Additionally, we observe significant in-plane spin polarization of the low-lying bulk bands, which is antisymmetric about the high-symmetry plane and contrary to the $d$-wave spin texture due to time-reversal symmetry breaking in altermagnetism. These findings definitively challenge the altermagnetic order previously proposed for rutile RuO$_2$, prompting a reevaluation of its magnetic properties.

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Jiayu Liu, Jie Zhan, Tongrui Li, Jishan Liu, Shufan Cheng, Yuming Shi, Liwei Deng, Meng Zhang, Chihao Li, Jianyang Ding, Qi Jiang, Mao Ye, Zhengtai Liu, Zhicheng Jiang, Siyu Wang, Qian Li, Yanwu Xie, Yilin Wang, Shan Qiao, Jinsheng Wen, Yan Sun, Dawei Shen. 2024-09-20. Absence of altermagnetic spin splitting character in rutile oxide RuO$_2$. https://doi.org/10.1103/physrevlett.133.176401

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