Termination-Preserved Ultra-high Tunneling Magnetoresistance in Altermagnetic KV2Se2O

TL;DR

This study demonstrates that KV2Se2O-based altermagnetic tunnel junctions can achieve ultra-high tunnel magnetoresistance ratios, up to 10^12%, through specific interfacial passivation and momentum-space topology coupling, advancing spintronic device performance.

Contribution

It reveals a novel mechanism for ultra-high TMR in altermagnetic tunnel junctions via interfacial passivation and momentum-space topology coupling, supported by first-principles calculations.

Findings

Achieved TMR above 105% for all interfacial terminations.

K-termination leads to TMR up to 10^12%.

Coupling between topology and passivation enhances magnetoresistive responses.

Abstract

Altermagnets exhibit nonrelativistic spin splitting without net magnetization, establishing a new platform for next-generation spintronic devices. Although altermagnetic tunnel junctions (AMTJs) represent the most promising realizations, their practical applications are hindered by low tunnel magnetoresistance (TMR) ratios and strong sensitivity to interfacial configurations. Here, we systematically explore the transport properties and microscopic mechanisms of AMTJs based on the recently discovered d-wave altermagnet KV2Se2O. Using first-principles calculations and orbital-resolved analysis, we demonstrate that the synergy between compressed nodal-point like spin-degenerate channels and coplanar interfacial magnetic order yields an ultra-high intrinsic TMR above 105% for all interfacial terminations. More importantly, K-termination effectively preserves bulk spin polarization through its unique passivation characteristics, leading to an ultra-high TMR up to 1012%. These results identify the coupling between momentum-space topology and interfacial passivation provides a reliable strategy for realizing giant magnetoresistive responses in altermagnetic spintronic devices.