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arXiv · 2002.09292

Magnetic-field-induced topological phase transition in Fe-doped (Bi,Sb)$_2$Se$_3$ heterostructures

Y. Satake·J. Shiogai·G. P. Mazur·S. Kimura·S. Awaji·K. Fujiwara·T. Nojima·K. Nomura·S. Souma·T. Sato·T. Dietl·A. Tsukazaki
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Abstract

Three-dimensional topological insulators (3D-TIs) possess a specific topological order of electronic bands, resulting in gapless surface states via bulk-edge correspondence. Exotic phenomena have been realized in ferromagnetic TIs, such as the quantum anomalous Hall (QAH) effect with a chiral edge conduction and a quantized value of the Hall resistance ${R_{yx}}$. Here, we report on the emergence of distinct topological phases in paramagnetic Fe-doped (Bi,Sb)${_2}$Se${_3}$ heterostructures with varying structure architecture, doping, and magnetic and electric fields. Starting from a 3D-TI, a two-dimensional insulator appears at layer thicknesses below a critical value, which turns into an Anderson insulator for Fe concentrations sufficiently large to produce localization by magnetic disorder. With applying a magnetic field, a topological transition from the Anderson insulator to the QAH state occurs, which is driven by the formation of an exchange gap owing to a giant Zeeman splitting and reduced magnetic disorder. Topological phase diagram of (Bi,Sb)${_2}$Se${_3}$ allows exploration of intricate interplay of topological protection, magnetic disorder, and exchange splitting.

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Y. Satake, J. Shiogai, G. P. Mazur, S. Kimura, S. Awaji, K. Fujiwara, T. Nojima, K. Nomura, S. Souma, T. Sato, T. Dietl, A. Tsukazaki. 2020-02-21. Magnetic-field-induced topological phase transition in Fe-doped (Bi,Sb)$_2$Se$_3$ heterostructures. https://doi.org/10.1103/physrevmaterials.4.044202

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