Colossal Spin Splitting in the Monolayer of the Collinear Antiferromagnet MnF2.

In this Letter we report on the colossal spin splitting (on the order of several electronvolts) in the collinear antiferromagnetic (AFM) MnF2 (110) monolayer, which we obtained from first-principles calculations and explain in terms of group-theoretical analysis. This Pekar-Rashba AFM-induced spin splitting with a magnetic mechanism does not require the presence of spin-orbit coupling such as with a traditional Rashba-Dresselhaus electric mechanism. Furthermore, it was observed for all wave vectors, including high-symmetry points of the two-dimensional (2D) Brillouin zone. This is in contrast to recently reported AFM-induced spin splitting in the bulk structure of MnF2, which was both smaller by at least an order of magnitude and required to vanish by symmetry at several high-symmetry points and directions of the three-dimensional Brillouin zone. The crucial part of our group-theoretical analysis is the determination of the magnetic layer group for the monolayer structure for which we propose a simple and generic procedure.