Quantum oscillations in topological superconductor candidate Cu$_{0.25}$Bi$_2$Se$_3$

TL;DR

This study reports the observation of quantum oscillations in Cu$_{0.25}$Bi$_2$Se$_3$, a candidate topological superconductor, using torque magnetometry, revealing that Cu doping does not alter the band structure of Bi$_2$Se$_3$.

Contribution

First observation of quantum oscillations in Cu$_{0.25}$Bi$_2$Se$_3$ via torque magnetometry, showing Cu doping preserves the band structure of Bi$_2$Se$_3$.

Findings

Quantum oscillations observed in Cu$_{0.25}$Bi$_2$Se$_3$

Cu doping increases carrier density and effective mass

Fermi velocity remains unchanged with Cu doping

Abstract

Quantum oscillations are generally studied to resolve the electronic structure of topological insulators. In Cu$_{0.25}$Bi$_2$Se$_3$, the prime candidate of topological superconductors, quantum oscillations are still not observed in magnetotransport measurement. However, using torque magnetometry, quantum oscillations (the de Hass - van Alphen effect) were observed in Cu$_{0.25}$Bi$_2$Se$_3$ . The doping of Cu in Bi$_2$Se$_3$ increases the carrier density and the effective mass without increasing the scattering rate or decreasing the mean free path. In addition, the Fermi velocity remains the same in Cu$_{0.25}$Bi$_2$Se$_3$ as that in Bi$_2$Se$_3$. Our results imply that the insertion of Cu does not change the band structure of Bi$_2$Se$_3$.