Spin-Valley-Mismatched Altermagnet for Giant Tunneling Magnetoresistance

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

paper

Spin-Valley-Mismatched Altermagnet for Giant Tunneling Magnetoresistance

arXiv:2604.14776

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 ( $k_{∥}$ )-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 $7.57 \times 1 0^{7}$ \%, 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.

8 pages, 5 figures. npj Computational Materials, in press