Quantum oscillations in metallic Sb2Te2Se topological insulator

TL;DR

This study investigates the magnetotransport properties of the topological insulator Sb2Te2Se, revealing quantum oscillations indicative of topological surface states and providing insights into its electronic structure and Fermi level positioning.

Contribution

It provides the first detailed analysis of quantum oscillations and Fermi surface characteristics in Sb2Te2Se, highlighting its topological surface states and electronic properties.

Findings

Observation of Shubnikov de Haas oscillations above 15 T

Identification of a 2D Fermi surface from tilt angle measurements

Fermi level located 250 meV above the Dirac point, near the bulk valence band

Abstract

We have studied the magnetotransport properties of the metallic, p-type Sb2Te2Se which is a topological insulator. Magnetoresistance shows Shubnikov de Haas oscillations in fields above B=15 T. The maxima/minima positions of oscillations measured at different tilt angles with respect to the B direction align with the normal component of field Bcosine, implying the existence of a 2D Fermi surface in Sb2Te2Se. The value of the Berry phase determined from a Landau level fan diagram is very close to 0.5, further suggesting that the oscillations result from topological surface states. From Lifshitz-Kosevich analyses, the position of the Fermi level is found to be EF =250 meV, above the Dirac point. This value of EF is almost 3 times as large as that in our previous study on the Bi2Se2:1Te0:9 topological insulator; however, it still touches the tip of the bulk valence band. This explains the metallic behavior and hole-like bulk charge carriers in the Sb2Te2Se compound.