The antiferromagnets with the time-reversal symmetry broken magnetic structures possess a finite spin splitting in the momentum space, and may contribute to a realization of a finite tunnel magnetoresistance (TMR) effect even with magnets with zero net spin polarization. In this paper, we study the TMR effect with the noncollinear antiferromagnet Mn3Sn whose inverse 120∘ antiferromagnetic order breaks the time-reversal symmetry. In particular, we employ the representative barrier material MgO as the tunnel insulator, and calculate the TMR effect in the Mn3Sn(011ˉ0)/MgO(110)/Mn3Sn magnetic tunnel junctions (MTJs), which has an optimal geometry for the spin-orbit torque switching of the magnetic configurations. We show that a finite TMR ratio reaching ≳1000% appears in the Mn3Sn/MgO/Mn3Sn MTJs, which is due to the spin splitting properties of Mn3Sn in the momentum space combined with the screening effect of MgO.
@article{arxiv.2509.21877,
title = {Ab initio study of magnetoresistance effect in $\mathrm{Mn_{3}Sn}/\mathrm{MgO}/\mathrm{Mn_{3}Sn}$ antiferromagnetic tunnel junction},
author = {Katsuhiro Tanaka and Yuta Toga and Susumu Minami and Satoru Nakatsuji and Takuya Nomoto and Takashi Koretsune and Ryotaro Arita},
journal= {arXiv preprint arXiv:2509.21877},
year = {2025}
}