Spin injection and magnetoresistance in MoS₂-based tunnel junctions using Fe₃Si Heusler alloy electrodes

Recently magnetic tunnel junctions using two-dimensional MoS₂ as nonmagnetic spacer have been fabricated, although their magnetoresistance has been reported to be quite low. This may be attributed to the use of permalloy electrodes, injecting current with a relatively small spin polarization. Here we evaluate the performance of MoS₂-based tunnel junctions using Fe₃Si Heusler alloy electrodes. Density functional theory and the non-equilibrium Green's function method are used to investigate the spin injection efficiency (SIE) and the magnetoresistance (MR) ratio as a function of the MoS₂ thickness. We find a maximum MR of ~300% with a SIE of about 80% for spacers comprising between 3 and 5 MoS₂ monolayers. Most importantly, both the SIE and the MR remain robust at finite bias, namely MR > 100% and SIE > 50% at 0.7 V. Our proposed materials stack thus demonstrates the possibility of developing a new generation of performing magnetic tunnel junctions with layered two-dimensional compounds as spacers.