Doping-dependent charge dynamics in CuxBi2Se3

TL;DR

This study investigates how copper doping affects the electronic structure of CuxBi2Se3, revealing increased effective mass and complex doping effects, which are crucial for understanding its superconducting properties.

Contribution

It provides a systematic optical spectroscopic analysis of Cu doping effects on the electronic structure of CuxBi2Se3, highlighting changes in effective mass and doping behavior.

Findings

Increase in conduction band effective mass with Cu doping

Stable free carrier density and lifetime beyond x=0.15

Complex nature of Cu doping effects in Bi2Se3

Abstract

Superconducting CuxBi2Se3 has attracted significant attention as a candidate topological superconductor. Besides inducing superconductivity, the introduction of Cu atoms to this material has also been observed to produce a number of unusual features in DC transport and magnetic susceptibility measurements. To clarify the effect of Cu doping, we have performed a systematic optical spectroscopic study of the electronic structure of CuxBi2Se3 as a function of Cu doping. Our measurements reveal an increase in the conduction band effective mass, while both the free carrier density and lifetime remain relatively constant for Cu content greater than x=0.15. The increased mass naturally explains trends in the superfluid density and residual resistivity as well as hints at the complex nature of Cu doping in Bi2Se3.