Magnetic Gap of Fe-Doped BiSbTe2Se Bulk Single Crystals Detected by Tunneling Spectroscopy and Gate-Controlled Transports

Rikizo Yano; Andrei Kudriashov; Hishiro T Hirose; Taiki Tsuda; Hiromi Kashiwaya; Takao Sasagawa; Alexander A Golubov; Vasily S Stolyarov; Satoshi Kashiwaya

doi:10.1021/acs.jpclett.1c00869

Magnetic Gap of Fe-Doped BiSbTe₂Se Bulk Single Crystals Detected by Tunneling Spectroscopy and Gate-Controlled Transports

J Phys Chem Lett. 2021 May 6;12(17):4180-4186. doi: 10.1021/acs.jpclett.1c00869. Epub 2021 Apr 26.

Authors

Rikizo Yano^{1

2}, Andrei Kudriashov³, Hishiro T Hirose⁴, Taiki Tsuda², Hiromi Kashiwaya⁵, Takao Sasagawa⁴, Alexander A Golubov^{3

6}, Vasily S Stolyarov^{3

7}, Satoshi Kashiwaya²

Affiliations

¹ Institute of Materials and Systems for Sustainability, Nagoya University, Nagoya 464-8603, Japan.
² Applied Physics, Nagoya University, Nagoya 464-8603, Japan.
³ TQPSS Lab, Center for Photonics and 2D Materials, Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Oblast 141700, Russia.
⁴ Laboratory for Materials and Structures, Tokyo Institute of Technology, Yokohama 226-8503, Japan.
⁵ National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8568, Japan.
⁶ Faculty of Science and Technology and MESA+ Institute of Nanotechnology, Enschede 7500 AE, The Netherlands.
⁷ Dukhov Research Institute of Automatics (VNIIA), Moscow 127055, Russia.

PMID: 33900082
DOI: 10.1021/acs.jpclett.1c00869

Abstract

Topological insulators with broken time-reversal symmetry and the Fermi level within the magnetic gap at the Dirac cone provides exotic topological magneto-electronic phenomena. Here, we introduce an improved magnetically doped topological insulator, Fe-doped BiSbTe₂Se (Fe-BSTS) bulk single crystal, with an ideal Fermi level. Scanning tunneling microscopy and spectroscopy (STM/STS) measurements revealed that the surface state possesses a Dirac cone with the Dirac point just below the Fermi level by 12 meV. The normalized dI/dV spectra suggest a gap opening with Δ_mag ∼55 meV, resulting in the Fermi level within the opened gap. Ionic-liquid gated-transport measurements also support the Dirac point just below the Fermi level and the presence of the magnetic gap. The chemical potential of the surface state can be fully tuned by ionic-liquid gating, and thus the Fe-doped BSTS provides an ideal platform to investigate exotic quantum topological phenomena.