1. Two-dimensional ferromagnetic extension of a topological insulator
- Author
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Kagerer, P., Fornari, C. I., Buchberger, S., Tschirner, T., Veyrat, L., Kamp, M., Tcakaev, A. V., Zabolotnyy, V., Morelhão, S. L., Geldiyev, B., Müller, S., Fedorov, A., Rienks, E., Gargiani, P., Valvidares, M., Folkers, L. C., Isaeva, A., Büchner, B., Hinkov, V., Claessen, R., Bentmann, H., and Reinert, F.
- Subjects
Condensed Matter - Materials Science - Abstract
Inducing a magnetic gap at the Dirac point of the topological surface state (TSS) in a 3D topological insulator (TI) is a route to dissipationless charge and spin currents. Ideally, magnetic order is present only at the surface and not in the bulk, e.g. through proximity of a ferromagnetic (FM) layer. However, such a proximity-induced Dirac mass gap has not been observed, likely due to insufficient overlap of TSS and the FM subsystem. Here, we take a different approach, namely FM extension, using a thin film of the 3D TI Bi$_2$Te$_3$, interfaced with a monolayer of the lattice-matched van der Waals ferromagnet MnBi$_2$Te$_4$. Robust 2D ferromagnetism with out-of-plane anisotropy and a critical temperature of $\text{T}_\text{c}\approx$~15 K is demonstrated by X-ray magnetic dichroism and electrical transport measurements. Using angle-resolved photoelectron spectroscopy, we observe the opening of a sizable magnetic gap in the 2D FM phase, while the surface remains gapless in the paramagnetic phase above T$_c$. This sizable gap indicates a relocation of the TSS to the FM ordered Mn moments near the surface, which leads to a large mutual overlap., Comment: 6 pages, 3 figures
- Published
- 2022
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