Substrate-Dependent Physical Properties at the Interface of Manganese(II) Phthalocyanine and Topological Insulators

A proper understanding of the physical properties at the interface between a nonmagnetic topological insulator and a magnetic film is an indispensable input to develop high-functional spintronics devices using topological insulators. In this paper, we show the physical properties of manganese(II) phthalocyanine (MnPc)-adsorbed Bi2Se3 and TlBiSe2, two topological insulators with similar electronic states but different surface compositions. The adsorption of MnPc induces significant electron doping on Bi2Se3, while only a small hole doping was induced on TlBiSe2. This difference in doping is due to the different molecular orientations on the two topological insulators: the flat-lying configuration on Bi2Se3 that leads to a large overlap between the d-orbital of Mn and orbitals of surface Se, and the upright configuration on TlBiSe2 that results from the presence of Tl atoms on the surface and leads to a negligible orbital overlap. These results pave the way for applications in spintronics devices combining magnetic organic molecules and topological insulators.