Neutron Investigations of the Antiferromagnet Topological Insulator, MnBi$_2$Te$_4$

In this talk, I discuss our recent results on the first intrinsic antiferromagnetic topological insulator, MnBi$_2$Te$_4$. In this Van der Waals material, we can control the magnetic state through chemical substitution, as well as through the application of a magnetic field. These knobs allow us to effect the topology of the band structure and thus the transport. We apply a number of probes, including transport, susceptibility, neutron scattering, ARPES, and TEM to determine the physics of this exciting material [1,2]. "Spin Scattering and noncollinear spin-structure induced intrinsic anomalous Hall Effect in antiferromagnetic topological insulator MnnBi2Te4, Seng Huat Lee et al, Phys. Rev. Research 1, 012011 (2019) "Ferromagnetism in van der Walls compound MnSb1.8Bi.2Te4" Yangyang Chen et al, Phys. Rev. Matt. 4, 064411 (2020)