Landau level spectroscopy of relativistic fermions with low Fermi velocity in Bi2Te3 three-dimensional topological insulator

TL;DR

This study uses microwave spectroscopy to observe Landau level transitions in Bi2Te3, revealing a notably low Fermi velocity and insights into surface state occupation influenced by band bending.

Contribution

It reports the first microwave spectroscopic measurement of Landau levels in Bi2Te3 with low Fermi velocity, linking surface state occupation to band bending effects.

Findings

Fermi velocity measured at 3260 m/s, lower than previous reports.

Landau level transitions observed via microwave spectroscopy.

Bulk Fermi level and surface band bending influence surface state occupation.

Abstract

X-band microwave spectroscopy is applied to study the cyclotron resonance in Bi2Te3 exposed to ambient conditions. With its help, intraband transitions between Landau levels of relativistic fermions are observed. The Fermi velocity equals to 3260 m/s, which is much lower than has been reported in the literature for samples cleaved in vacuum. Simultaneous observation of bulk Shubnikov - de Haas oscillations by contactless microwave spectroscopy allows determination of the Fermi level position. Occupation of topological surface states depends not only on bulk Fermi level but also on the surface band bending.