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arXiv · 2604.14776

Spin-Valley-Mismatched Altermagnet for Giant Tunneling Magnetoresistance

Kun Yan·Yizhi Hu·Wei-Hua Xiao·Xiaolong Zou·Xiaobin Chen·Wenhui Duan
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Abstract

Altermagnet-based heterojunctions have demonstrated magnetoresistive effects in experiments, however, a predictive theoretical model for non-ferromagnetic structures has remained elusive. In this work, we develop a tunneling-based spin-transport theory that explicitly incorporates the transverse-wavevector ($\bf{k}_\|$)-dependent spin polarization of an altermagnet's transport channels, enabling the prediction of giant tunneling magnetoresistance (TMR). Based on the theory, we predict that the altermagnet KV$_2$Se$_2$O can reach the extreme limit of magnetoresistance. By performing first-principles transport calculations, we verify that magnetic tunnel junctions using the metallic KV$_2$Se$_2$O as the electrodes and few-layer MgO as the spacer exhibit zero-bias magnetoresistance larger than $7.57\times10^7$\%, which is robust against the bias and thickness of the spacer. Our research provides a quantitative design principle for next-generation spin-electronic devices and establishes KV$_2$Se$_2$O/MgO/KV$_2$Se$_2$O as a leading candidate material system for room-temperature ultra-high-density non-volatile memory.

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Kun Yan, Yizhi Hu, Wei-Hua Xiao, Xiaolong Zou, Xiaobin Chen, Wenhui Duan. 2026-04-16. Spin-Valley-Mismatched Altermagnet for Giant Tunneling Magnetoresistance. https://arxiv.org/abs/2604.14776

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