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Topological insulators (TIs) are fascinating materials due to their protected edge-states and their possibilities for spintronic applications. Spin-orbit coupling and exchange effects at interfaces give us a possibility to tailor the properties of two-dimensional (2D) topological materials. While magnetism is usually detrimental to the topological properties, we show that exchange interactions offer the possibility to realize a variety of new phases depending on the structural symmetry and the direction of the magnetic (exchange) field. Using density functional theory we explore the quantum spin Hall to quantum anomalous Hall state transition in TIs and topological crystalline insulators. We propose the existence of new states like mixed nodal-line semimetals or mixed Weyl semimetals in the phase diagram of these 2D materials, showing interesting magnetoelectric coupling phenomena as function of the magnetization direction.

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Gustav Bihlmayer, FZ Jülich
Seminar Room of the Institute of Physics II
Contact: Alexander Grüneis