Dresden 2020 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 8: Topological Phenomena (joint session MA/TT)

TT 8.4: Vortrag

Montag, 16. März 2020, 10:15–10:30, POT 6

A Family of Intrinsic Magnetic Topological Insulators (MnBi2Te4)(Bi2Te3)n, n = 0, 1, 2 — •Anna Isaeva1, 2, Alexander Zeugner3, Anja U. B. Wolter1, Bernd Büchner1, and Hendrik Bentmann41Institute for Solid State and Materials Research, Leibniz IFW Dresden, Dresden, Germany — 2Faculty of Physics, Technische Universität Dresden, Dresden, Germany — 3Faculty of Chemistry and Food Chemistry, Technische Universität Dresden, Dresden, Germany — 4Experimental Physics VII, Universität Würzburg, Würzburg, Germany

In a quest to harness quantum effects for technological advances, new realizations of materials for quantum anomalous Hall effect are pursued. A family of van-de-Waals (MnBi2Te4)(Bi2Te3)n compounds derive from the 3D topological insulator Bi2Te3 and feature an ordered Mn sublattice. They are the first intrinsic magnetic topological insulators [1]. We obtain high-quality crystals for all n. (MnBi2Te4)(Bi2Te3)n are thermodynamically stable in narrow temperature ranges near 873 K. We establish ubiquitous off-stoichiometry of the materials, e.g. Mn1−xBi2+2x/3Te4 (x = 0.15). Temperature- and field-dependent magnetization measurements show a 3D antiferromagnetic order (TN = 24 K) in MnBi2Te4. It originates from an AFM interlayer coupling of Mn(II) layers with ferromagnetic intralayer coupling. This magnetic ground state and a centrosymmetric space group R3m entail the Z2 = 1 topological classification and render MnBi2Te4 the first AFM TI [1]. [1] M. Otrokov et al. Nature (2019), in press, arxiv.org: 1809.07389.

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