SKM 2023 – scientific programme
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O: Fachverband Oberflächenphysik
O 94: Topology and Symmetry-Protected Materials
O 94.6: Talk
Friday, March 31, 2023, 11:45–12:00, GER 38
The 2D Ferromagnetic Extension of a Topological Insulator — •Philipp Kagerer1,2, Celso I. Fornari1,2, Sebastian Buchberger1,2, Begmuhammet Geldiyev1,2, Teresa Tschirner2,3, Louis Veyrat2,3,4, Abdul V. Tcakaev2,4, Martin Kamp5, Sergio L. Morelhao6, Vladimir Hinkov2,4, Hendrik Bentmann1,2, and Friedrich Reinert1,2 — 1Exp. Physik VII, Universität Würzburg — 2Würzburg-Dresden Cluster of Excellence ct.qmat — 3Leibnitz IFW Dresden — 4Exp. Physik IV, Universität Würzburg — 5Physikalisches Institut and RCCM, Universität Würzburg — 6Instituto de Física, Universidade de São Paulo
3D topological insulators (TI) are known to have a topological non-trivial band structure protected by time reversal symmetry, which also guarantees the metallicity of the surface. Consequently, it is sufficient to break this symmetry only locally at the surface of the sample to gap out the topological surface state (TSS), leading to a variety of novel topological effects, e.g. an axion term in the electromagnetic response and quantized spin-selective edge channels.
While most experimental approaches to date have aimed to introduce magnetism globally, we present the first experimental realisation of the ferromagnetic extension (1), a design directly interfacing a 3D TI with a two-dimensional non-trivial magnet. Utilizing a single septuple layer MnBi2Te4 on the prototypical TI Bi2Te3, we establish a stable 2D ferromagnetic ground state and introduce a sizeable magnetic exchange gap in the TSS (2).
(1) M.M. Otrokov et al., 2D Mater. 4, 025082 (2017)
(2) P. Kagerer et al., arXiv 2207.14421 (2022)