Quantum Cafe: Nadya Mason

Title: Surface State Magnetoresistance in 3D Topological Insulators

Abstract: Topological insulators (TIs) have a variety of unique transport properties, including strong spin-orbit coupling and symmetry-protected spin-momentum locked surface states. These properties have driven significant interest in understanding the science and device potential of systems that combine TIs with magnetism. In this talk, I will first describe how a parallel magnetic field through a TI wire leads to Aharonov-Bohm oscillations, indicative of ballistic surface transport. I will then discuss how proximity magnetization— i.e., placing a layer of magnetic material in direct contact with the TI—can be used to control the surface state symmetry, and thus the transport properties. In particular, for the TI Bi2Se3 on the magnetic insulator YIG, we experimentally observe a new MR effect, that is identified as anisotropic magnetoresistance consistent with a magnetized surface state. The result is consistent with magnetic anisotropy out of the sample plane opening an energy gap between the surface states and provides insights into the fundamental mechanisms of magnetic proximity and interface interactions in topological systems.

For Zoom details please contact Mary Kate Hennelly at [email protected]