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arXiv · 2602.21460

Intrinsic Spin Filter Effect in a $d$-wave altermagnet KV$_2$Se$_2$O with Open Fermi Surface

Bin Liu·Pei-Hao Fu·Yu-Xuan Sun·Xiao-Lin Zhang·Si-Cong Zhu·Xiang-Long Yu·Hua Wu·Yuan-Zhi Shao
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Abstract

Altermagnets offer a unique pathway to functional spintronics by combining vanishing magnetization with large spin splitting. Here, we demonstrate that the canonical d-wave altermagnet KV2Se2O can deliver giant tunneling magnetoresistance through orientation-dependent spin filtering. By analyzing the crystallographic spin segregation, we show that transport along specific crystallographic axes is nearly fully spin-polarized within the symmetry-protected ballistic channels. We implement this mechanism in a lattice-matched KV2Se2O/Bi2O2Se/KV2Se2O magnetic tunnel junction, which achieves a robust half-metallic transport regime. The symmetry-protected spectral gap in the parallel/anti-parallel configuration ensures a high tunneling magnetoresistance ratio, resulting in substantial tunneling magnetoresistance, robust thermally driven spin filtering, and spin Seebeck effect at room temperature. These findings provide a path of altermagnetic heterostructures as a high-performance platform for scalable, field-free, and thermally stable spin logic.

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Bin Liu, Pei-Hao Fu, Yu-Xuan Sun, Xiao-Lin Zhang, Si-Cong Zhu, Xiang-Long Yu, Hua Wu, Yuan-Zhi Shao. 2026-02-25. Intrinsic Spin Filter Effect in a $d$-wave altermagnet KV$_2$Se$_2$O with Open Fermi Surface. https://arxiv.org/abs/2602.21460

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