Large magnetoresistance of MnBi/Bi/MnBi spin valve

A transport magetoresistance (MR) of MnBi/Bi/MnBi spin valve device was calculated using density functional theory coupled with nonequilibrium Greens function method. The calculated transmission MR of the MnBi/Bi/MnBi spin valve device is around 750%, Obtained MR is very large compared with MR observed experimentally in MnBi junctions at room temperature (MR~70%). Large MR is consistent with a large transport spin polarization was demonstrated in MnBi films by the point contact Andreev reflection spectroscopy. MR of experimental point contacts is observed to be low is probably due to the rough interfaces that increased scattering and contact resistance. Consequently, a spin-valve MnBi/Bi/MnBi device could potentially have large MR that could be controlled by varying the thickness of the Bi spacer. Thus, MnBi is a promising candidate for high MR devices with tunable spacer properties.