Optical study on topological superconductor candidate Sr-doped Bi2Se3 |
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| Affiliation: | 1.Center for Advanced Quantum Studies and Department of Physics, Beijing Normal University, Beijing 100875, China;2.International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China;3.Collaborative Innovation Center of Quantum Matter, Beijing 100871, China |
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| Abstract: | Utilizing infrared spectroscopy, we study the charge dynamics of the topological superconductor candidate Sr$_x$Bi$_2$Se$_3$. The frequency-dependent reflectivity $R(omega$) demonstrates metallic feature and the scattering rate of the free carriers decreases with temperature decreasing. The plasma edge shows a slight blue shift upon cooling, similar to the behavior of Cu$_x$Bi$_2$Se$_3$. As the carrier concentration $n$ obtained by Hall resistivity increases slightly with the decreasing temperature, the effective mass is proved to increase as well, which is in contrast with that of Cu$_x$Bi$_2$Se$_3$.We also perform the ultrafast pump-probe study on the Sr$_{0.2}$Bi$_2$Se$_3$ compounds. Resembling its parent compound Bi$_2$Se$_3$, three distinct relaxation processes are found to contribute to the transient reflectivity. However, the deduced relaxation times are quite different. In addition, the electron-optical-phonon coupling constant is identified to be $lambda = 0.88$. |
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| Keywords: | topological superconductor infrared spectroscopy ultrafast spectroscopy |
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