Quantum oscillations with non-zero Berry phase from a complex three dimensional Fermi surface in Bi2Te3

TL;DR

This study investigates quantum oscillations in Bi2Te3, revealing a complex 3D Fermi surface and topological surface states with a non-zero Berry phase, while also analyzing asymmetric magnetoresistance effects.

Contribution

It provides new insights into the angular dependence of quantum oscillations and magnetoresistance in Bi2Te3, highlighting a complex Fermi surface beyond simple models.

Findings

Quantum oscillations indicate topological surface states with non-zero Berry phase.

Magnetoresistance asymmetry is linked to Hall voltage mixing and varies with environmental exposure.

Quantum oscillations are robust against atmospheric and thermal effects.

Abstract

We performed angle dependent magnetoresistance study of a metallic single crystal sample of Bi2Te3. We find that the magnetoresistance is highly asymmetric in positive and negative magnetic fields for small angles between the magnetic field and the direction perpendicular to the plane of the sample. The magnetoresistance becomes symmetric as the angle approaches 90 degree. The quantum Shubnikov de-Haas oscillations are symmetric and show signatures of topological surface states with Dirac dispersion in the form of non-zero Berry phase. However, the angular dependence of these oscillations suggests a complex three dimensional Fermi surface as the source of these oscillations, which does not exactly conform with the six ellipsoidal model of the Fermi surface of Bi2Te3. We attribute the asymmetry in the magnetoresistance to a mixing of the Hall voltage in the longitudinal resistance due to the comparable magnitude of the Hall and longitudinal resistance in our samples. This provides a clue to understanding the asymmetric magnetoresistance often seen in this and similar materials. Moreover, the asymmetric nature evolves with exposure to atmosphere and thermal cycling, which we believe is either due to exposure to atmosphere or thermal cycling, or both affecting the carrier concentration and hence the Hall signal in these samples. However, the quantum oscillations seem to be robust against these factors which suggests that the two have different origins.