David Lederman1,Ryan Van Haren1
University of California, Santa Cruz1
David Lederman1,Ryan Van Haren1
University of California, Santa Cruz1
Magnetic proximity effects between topological insulators and insulating antiferromagnets can open the way to new spintronic functionalities, including THz communication and data storage technology. Here we report on magnetotransport measurements of MnF<sub>2</sub>/(Bi,Sb)<sub>2</sub>Te<sub>3</sub> antiferromagnetic/ topological insulator heterostructures. MnF<sub>2</sub> is a canonical uniaxial antiferromagnet with a tetragonal crystal structure, whereas (Bi,Sb)<sub>2</sub>Te<sub>3</sub> is a topological insulator whose Fermi level can be brought into the bulk gap to access the topologically-protected surface states by varying the Sb concentration. The samples were grown using molecular beam epitaxy on MgF2 (110) substrates. The MnF<sub>2</sub> layer was grown epitaxially the substrate using a (Mn,Ni)F<sub>2</sub> graded layer to reduce the strain on the MnF<sub>2</sub>, resulting in (110) growth with the [001] crystallographic direction in the plane of the sample, corresponding to the magnetic anisotropy easy axis. We find evidence for coupling between the MnF<sub>2</sub> layer and the (Bi,Sb)<sub>2</sub>Te<sub>3</sub> surface states by measuring the planar Hall effect with the external magnetic field applied parallel to the MnF<sub>2</sub> easy axis, where a sudden change is measured at the MnF<sub>2</sub> spin-flop field. We will also present measurements with the field perpendicular to the plane of the samples, where the Hall effect is observed. Possible interpretations of these measurements and the influence of the topological nature of the surface state carriers will be discussed.<br/><br/>This work was supported in part by the Air Force MURI program, grant number FA9550-19-454963.