Quantum oscillations are generally studied to resolve the electronic structure of topological insulators. In ${\mathrm{Cu}}_{0.25}{\mathrm{Bi}}_2{\mathrm{Se}}_3$, the prime candidate of topological superconductors, quantum oscillations are still not observed in magnetotransport measurement. However, using torque magnetometry, quantum oscillations (the de Haas–van Alphen effect) were observed in ${\mathrm{Cu}}_{0.25}{\mathrm{Bi}}_2{\mathrm{Se}}_3$. The doping of Cu in ${\mathrm{Bi}}_2{\mathrm{Se}}_3$ 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 ${\mathrm{Cu}}_{0.25}{\mathrm{Bi}}_2{\mathrm{Se}}_3$ as that in ${\mathrm{Bi}}_2{\mathrm{Se}}_3$. Our results imply that the insertion of Cu does not change the band structure and that conduction electrons in Cu doped ${\mathrm{Bi}}_2{\mathrm{Se}}_3$ sit in the linear Dirac-like band.

• Received 2 July 2012

DOI:https://doi.org/10.1103/PhysRevLett.109.226406