Phys.org  August 9, 2024 The indirect exchange interaction between local magnetic moments via surface electrons has been long predicted to bolster the surface ferromagnetism in magnetic topological insulators (MTIs), which facilitates the quantum anomalous Hall effect. This unconventional effect is critical to determining the operating temperatures of future topotronic devices. However, the experimental confirmation of this mechanism has not been investigated in intrinsic MTIs. An international team of researchers (University of Chicago, University of Florida, Pennsylvania State University, Israel) combined time-resolved photoemission spectroscopy with time-resolved magneto-optical Kerr effect measurements to explain the unique electromagnetism at the surface of an intrinsic […]