Prediction of giant tunneling magnetoresistance in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>Ru</mml:mi><mml:msub><mml:mi mathvariant="normal">O</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:mo>/</mml:mo><mml:mi>Ti</mml:mi><mml:msub><mml:mi mathvariant="normal">O</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:mo>/</mml:mo><mml:mi>Ru</mml:mi><mml:msub><mml:mi mathvariant="normal">O</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:mrow></mml:math> (110) antiferromagnetic tunnel junctions
Yuanyuan Jiang, Zian Wang, Kartik Samanta, Shu‐Hui Zhang, Rui‐Chun Xiao, W. J. Lu, Yuping Sun, Evgeny Y. Tsymbal, Ding‐Fu Shao
Abstract
Using first-principles quantum-transport calculations, we investigate spin-dependent electronic and transport properties of antiferromagnetic tunnel junctions (AFMTJs) that consist of (110)-oriented antiferromagnetic (AFM) metal $\mathrm{Ru}{\mathrm{O}}_{2}$ electrodes and an insulating $\mathrm{Ti}{\mathrm{O}}_{2}$ tunneling barrier. We predict the emergence of a giant tunneling magnetoresistance (TMR) effect in a wide energy window, a series of barrier layer thicknesses, and different interface terminations, indicating the robustness of this effect. We show that the predicted TMR cannot be explained in terms of the global transport spin-polarization of $\mathrm{Ru}{\mathrm{O}}_{2}$ (110) but is well understood based on matching the momentum-dependent spin-polarized conduction channels of the two $\mathrm{Ru}{\mathrm{O}}_{2}$ (110) electrodes. We predict oscillations of TMR with increasing barrier thickness, indicating a non-negligible contribution from the perfectly epitaxial interfaces. Our work helps the understanding of the physics of TMR in AFMTJs and aids in realizing efficient AFM spintronic devices.