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arXiv · 2302.14228

A field-induced reentrant insulator state of a gap-closed topological insulator (Bi_{1-x}Sb_x) in quantum-limit states

Y. Kinoshita·T. Fujita·R. Kurihara·A. Miyake·Y. Izaki·Y. Fuseya·M. Tokunaga
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Abstract

In the extreme quantum limit states under high magnetic fields, enhanced electronic correlation effects can stabilize anomalous quantum states. Using band-tuning with a magnetic field, we realized a spin-polarized quantum limit state in the field-induced semimetallic phase of a topological insulator Bi_{1-x}Sb_x. Further increase in the field injects more electrons and holes to this state and results in an unexpected reentrant insulator state in this topological semimetallic state. A single-particle picture cannot explain this reentrant insulator state, reminiscent of phase transitions due to many-body effects. Estimates of the binding energy and spacing of electron-hole pairs and the thermal de Broglie wavelength indicate that Bi_{1-x}Sb_x may host the excitonic insulator phase in this extreme environment.

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Y. Kinoshita, T. Fujita, R. Kurihara, A. Miyake, Y. Izaki, Y. Fuseya, M. Tokunaga. 2023-02-28. A field-induced reentrant insulator state of a gap-closed topological insulator (Bi_{1-x}Sb_x) in quantum-limit states. https://doi.org/10.1103/physrevb.107.125140

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