2026/07/23 by Katsuhiro Tanaka, Takuya Nomoto, Ryotaro Arita
#cond-mat.mtrl-sci #cond-mat.mes-hall
Antiferromagnets can have a finite spin-polarization in the momentum space when their magnetic structure breaks the macroscopic time-reversal symmetry. This spin-polarization can produce a spin-polarized electric current even in antiferromagnets with vanishingly small net magnetizaton, which supports the antiferromagentic tunnel magnetoresistance (TMR) effect. In this paper, using first-principles calculations, we study the TMR effect with a doped altermagnet Ru1-xCrxO2 with (110) orientation, whose collinear antiferromagnetic structure breaks the time-reversal symmetry macroscopically. The momentum-dependent spin-polarization combined with the (110) crystal orientation makes the electric current spin-polarized through bulk Ru1-xCrxO2(110). We further calculate the TMR effect in the Ru1-xCrxO2(110)/\mathrmTiO2(110)/Ru1-xCrxO2(110) tunnel junction and show that a finite TMR effect emerges. Based on the analysis of the tunneling transport, the TMR effect is attributed to the spin polarized tunneling transport with momentum dependence and the interfacial magnetic structures, as well as the spin-polarized electric current in a bulk form of Ru1-xCrxO2(110).