Identification of Lifshitz transition, quantum oscillations, and metal-insulator transition in a composite topological matter Bi4(Br0.2I0.8)4

Abstract

Exploring the electronic transport behavior in the topological matter is of crucial interest in the region of both fundamental research and potential applications. In this work, we perform a systematical investigation of the transport properties of the new discovered topological material with both high-order topological insulating order and strong topological insulating order, Bi₄(Br_0.2I_0.8)₄, by applying the physical properties measurement system. A sign change of charge carriers with the variation of temperature is observed, which is ascribed to the Lifshitz transition and confirmed by the temperature-dependent angle-resolved photoemission spectroscopy measurements. The behavior of Shubnikov-de Hass oscillations occurs at a lower magnetic field region compared to the undoped Bi₄Br₄ parent phase, inferring the shrunk Fermi surface by introducing I dopant. After entering the extreme quantum limit, the metal-insulator transition is evoked by the possible finite electron-electron interaction with the further increment of magnetic field. The relationship among the Lifshitz transition, quantum oscillations, and metal-insulator transition is discussed to resolve the potential mechanism of quantum transport behaviors in Bi₄(Br_0.2I_0.8)₄. Our work provides the important references for modulating the quantum transport properties of topological matters in the future.