Tunneling magnetoresistance in all-antiferromagnetic Mn2 Au-based tunnel junctions

Antiferromagnetic (AF) spintronics offers the advantages of ultrahigh operating speed and stability to a device in the presence of a magnetic field. To fully exploit these advantages, the device should be comprised of all-AF materials. Although achieving a noticeable magnetoresistance (MR) effect in an all-AF device is difficult, this effect is essential for AF spintronic applications. Herein, we investigated the tunneling MR (TMR) effect in all-AF $\mathrm{Nb}\text{/}{\mathrm{Mn}}_{2}\mathrm{Au}\text{/}\mathrm{CdO}\text{/}{\mathrm{Mn}}_{2}\mathrm{Au}\text{/}\mathrm{Nb}$ magnetic tunnel junctions (MTJs) using first-principles scattering theory. Through calculations, we predicted the presence of high TMR, which was found to be of the order of $1000%$ in the case of some symmetric junctions. This could be attributed to the interfacial resonance-tunneling effect related to the ${k}_{||}$-dependent complex band structures of CdO and ${\mathrm{Mn}}_{2}\mathrm{Au}$ and to the high spin polarization of the interfacial magnetic atoms. Moreover, we studied the effects of voltage bias and interfacial disorder, such as oxygen vacancies, manganese vacancies, and manganese--cadmium exchanges, at the ${\mathrm{Mn}}_{2}\mathrm{Au}\text{/}\mathrm{CdO}$ interface. Our findings indicate that all-AF $\mathrm{Nb}\text{/}{\mathrm{Mn}}_{2}\mathrm{Au}\text{/}\mathrm{CdO}\text{/}{\mathrm{Mn}}_{2}\mathrm{Au}\text{/}\mathrm{Nb}$ MTJs are highly promising materials for spintronic applications and that rocksalt CdO is a potential symmetry-filtering material for such applications.