Tunneling conductance in two-dimensional junctions between a normal metal and a ferromagnetic Rashba metal

We have studied charge transport in ferromagnetic Rashba metal (FRM), where both Rashba type spin-orbit coupling (RSOC) and exchange coupling coexist. It has nontrivial metallic states, i.e., normal Rashba metal (NRM), anomalous Rashba metal (ARM), and Rashba ring metal (RRM), and they are manipulated by tuning the Fermi level with an applied gate voltage. We theoretically studied tunneling conductance (G) in a normal metal / FRM junction by changing the Fermi level via an applied gate voltage (Vg) on the FRM. We found a wide variation in the Vg dependence of G, which depends on the metallic states. In NRM, the Vg dependence of G is the same as that in a conventional two-dimensional system. However, in ARM, the Vg dependence of G is similar to that in a conventional one (two)-dimensional system for a large (small) RSOC. Furthermore, in RRM, which is generated by a large RSOC, the Vg dependence of the $G$ is similar to that in the one-dimensional system. In addition, these anomalous properties stem from the spin-momentum locking of RSOC rather than the density of states in ARM and RRM because of the large RSOC and exchange coupling.