SurfaceScience21 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 23: Poster Session II: Topology and symmetry-protected materials
O 23.3: Poster
Montag, 1. März 2021, 13:30–15:30, P
Observation of backscattering induced by magnetism in a topological edge state — •Berthold Jaeck1,2, Yonglong Xie1,3, Bogdan Andrei Bernevig1, and Ali Yazdani1 — 1Princeton University, Joseph Henry Laboratories and Department of Physics, Princeton, USA — 2Present Address: The Hong Kong University of Science and Technology, Department of Physics, Clearwater Bay, Kowloon, Hong Kong — 3Present Address: Harvard University, Department of Physics, Cambridge, USA
We have investigated the effects of time-reversal symmetry breaking on the topological edge state of bismuth. Using spectroscopic imaging and spin-polarized measurements with the STM, we have compared quasiparticle interference (QPI), occurring in the edge state of a pristine bismuth bilayer with that occurring in the edge state of a bilayer, which is terminated by ferromagnetic iron clusters. Our experiments on the decorated bilayer edge reveal an additional QPI branch that can be associated with spin-flip scattering across the Brioullin zone center between time-reversal band partners. The observed QPI characteristics exactly match with theoretical expectations for a topological edge state, having one Kramer’s pair of bands. Our results provide further evidence for the non-trivial nature of bismuth and, in particular, demonstrate backscattering inside a helical topological edge state induced by broken TRS through local magnetism (1).
This work is supported by the ONR, the Moore foundation, NSF-DMR, NSF-MRSEC and the Humboldt foundation.
(1) B. Jäck et al., PNAS 117 (28), 16214-16218 (2020)