Proximity effect between a topological insulator and a magnetic insulator with large perpendicular anisotropy.

We report that thin films of a prototype topological insulator, Bi₂Se₃, can be epitaxially grown onto the (0001) surface of BaFe₁₂O₁₉ (BaM), a magnetic insulator with high Curie temperature and large perpendicular anisotropy. In the Bi₂Se₃ 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 Bi₂Se₃/BaM heterostructures the low field MR is parabola-shaped, which is positive in perpendicu- lar 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 Bi₂Se₃/BaM interface. [ABSTRACT FROM AUTHOR]