We report that thin films of a prototype topological insulator, Bi$_{ 2}$Se$_{ 3}$, can be epitaxially grown onto the (0001) surface of BaFe$_{ 12}$O$_{ 19}$(BaM), a magnetic insulator with high Curie temperature and large perpendicular anisotropy. In the Bi$_2$Se$_3$ thin films grown on non-magnetic substrates, classic weak antilocalization (WAL) is manifested as cusp-shaped positive magnetoresistance (MR) in perpendicular magnetic fields and parabola-shaped positive MR in parallel fields, whereas in Bi$_{ 2}$Se$_{ 3}$/BaM heterostructures the low field MR is parabola-shaped, which is positive in perpendicular fields and negative in parallel fields. The magnetic field and temperature dependence of the MR is explained as a consequence of the suppression of WAL due to strong magnetic interactions at the Bi$_{ 2}$Se$_{ 3}$/BaM interface.
Categories: cond-mat.mes-hall