Exchange field effects on the electronic properties of heterostructured ferromagnetic/topological crystalline insulator

In this paper, the exchange field effects are theoretically investigated to generate the mass in ferromagnetic/topological crystalline insulator SnTe heterostructure. The Dirac theory of exchange field-induced system predicts the anisotropic gaps in both low- and high-energy regimes. At small momenta, the group velocity is anisotropic, coinciding with orientation-dependent Fermi velocities, however; it increases (decreases) when the magnetization vector is parallel (antiparallel) to the host spin direction. Further, we found that the effective mass is anisotropic as well and y-direction is responsible for the heavy-mass band around Dirac points. Moreover, the proximity coupling leads to the switching of the effective mass sign at small momenta due to the band gap opening and concavity changing of bands. Additionally, a decreasing behavior for effective mass with exchange field strength is seen independently of the direction.