Magneto-transport in copper-doped noncentrosymmetric BiTeI

TL;DR

This study investigates how copper doping affects the magneto-transport properties of BiTeI, revealing improved crystal quality, distinct Fermi surface features, and insights into the Rashba spin splitting mechanism.

Contribution

It provides new experimental data on copper-doped BiTeI, showing how doping influences crystal quality and electronic properties, and links structural parameters to Rashba spin splitting.

Findings

Copper doping enhances crystal quality and mobility.

Two Fermi surface frequencies observed in Shubnikov-de Haas oscillations.

Structural parameters, especially Bi-Te bond length, influence Rashba spin splitting.

Abstract

BiTeI exhibits large Rashba spin splitting due to its noncentrosymmetric crystal structure. The study of chemical doping effect is important in order to either tune the Fermi level or refine the crystal quality. Here, we report the magneto-transport measurement in high quality BiTeI single crystals with different copper dopings. We found that a small amount of copper doping improves the crystal quality significantly, which is supported by the transport data showing higher Hall mobility and larger amplitude in Shubnikov-de Haas oscillation at low temperature. Two distinct frequencies in Shubnikov-de Haas oscillation were observed giving extremal Fermi surface areas of $A_{S} = 9.1 \times 10^{12}$ cm$^{-2}$ and $A_{L} = 3.47\times 10^{14}$ cm$^{-2}$ with corresponding cyclotron masses $m_S^*$ = 0.0353 $m_e$ and $m_L^*$ = 0.178 $m_e$, respectively. Those results are further compared with relativistic band structure calculations using three reported Te and I refined or calculated positions. Our analysis infers the crucial role of Bi-Te bond length in the observed large bulk Rashba-type spin splitting effect in BiTeI.