Transport Signatures of Fermi Surface Topology Change in BiTeI

TL;DR

This study reveals how the Fermi surface topology change in BiTeI affects its magnetotransport properties, demonstrating a clear resistivity signature linked to the Dirac node and Fermi surface evolution under magnetic fields.

Contribution

It provides the first direct transport evidence of Fermi surface topology change in a Rashba semiconductor through systematic Fermi level tuning and magnetotransport measurements.

Findings

Resistivity increases/decreases when $E_F$ is above/below the Dirac node.

Identification of the Dirac node via Shubnikov-de Haas oscillations.

Violation of Kohler's rule reveals temperature effects on quantum magnetoresistance.

Abstract

We report a quantum magnetotransport signature of a change in Fermi surface topology in the Rashba semiconductor BiTeI with systematic tuning of the Fermi level $E_F$. Beyond the quantum limit, we observe a marked increase/decrease in electrical resistivity when $E_F$ is above/below the Dirac node that we show originates from the Fermi surface topology. This effect represents a measurement of the electron distribution on the low-index ($n=0,-1$) Landau levels and is uniquely enabled by the finite bulk $k_z$ dispersion along the $c$-axis and strong Rashba spin-orbit coupling strength of the system. The Dirac node is independently identified by Shubnikov-de Haas oscillations as a vanishing Fermi surface cross section at $k_z=0$. Additionally we find that the violation of Kohler's rule allows a distinct insight into the temperature evolution of the observed quantum magnetoresistance effects.