Determination of the surface states from the ultrafast electronic states in a thermoelectric material |
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| Authors: | Tongyao Wu Hongyuan Wang Yuanyuan Yang Shaofeng Duan Chaozhi Huang Tianwei Tang Yanfeng Guo Weidong Luo Wentao Zhang |
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| Affiliation: | 1.Key Laboratory of Artificial Structures and Quantum Control(Ministry of Education), Shenyang National Laboratory for Materials Science, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China;2.School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China;3.Institute of Natural Sciences, Shanghai Jiao Tong University, Shanghai 200240, China |
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| Abstract: | We reveal the electronic structure in YbCd2Sb2, a thermoelectric material, by angle-resolved photoemission spectroscopy (ARPES) and time-resolved ARPES (trARPES). Specifically, three bulk bands at the vicinity of the Fermi level are evidenced near the Brillouin zone center, consistent with the density functional theory (DFT) calculation. It is interesting that the spin-unpolarized bulk bands respond unexpectedly to right- and left-handed circularly polarized probe. In addition, a hole band of surface states, which is not sensitive to the polarization of the probe beam and is not expected from the DFT calculation, is identified. We find that the non-equilibrium quasiparticle recovery rate is much smaller in the surface states than that of the bulk states. Our results demonstrate that the surface states can be distinguished from the bulk ones from a view of time scale in the nonequilibrium physics. |
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| Keywords: | electronic band structure YbCd2Sb2 surface states time- and angle-resolved photoemission spectroscopy |
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