Spin-Orbit Coupling Driven Magnetic Response in Altermagnetic RuO 2 .

The recent prediction of the new magnetic class, altermagnetism, has drawn considerable interest, fueled by its potential to host novel phenomena and to be utilized in next-generation spintronics devices. Among many promising candidates, rutile RuO ₂ is a prototypical candidate for realizing the prospects of altermagnetism. However, the experimental studies on RuO ₂ are still in the early stages. In this study, the magnetic responses in RuO ₂ film are investigated by the Planar Hall effect (PHE). By rotating the external field (H _ext ), the PHE exhibits twofold behaviors. Moreover, the planar Hall conductivity shows a nonlinear response to the H _ext . These observed features in PHE resemble those in ferromagnet and topologically nontrivial systems, suggesting the field-induced magnetic response in rutile antiferromagnet. The work provides a strategy for detecting intriguing magnetic responses in altermagnetic materials, promoting further research in altermagnet-based spintronics and novel phenomena.
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