TY - JOUR
T1 - Electronic structures of Bi2Se3 and AgxBi2Se3 under pressure studied by high-resolution X-ray absorption spectroscopy and density functional theory calculations
AU - Yamaoka, Hitoshi
AU - Jeschke, Harald O.
AU - Yang, Xiaofan
AU - He, Tong
AU - Goto, Hidenori
AU - Hiraoka, Nozomu
AU - Ishii, Hirofumi
AU - Mizuki, Jun'ichiro
AU - Kubozono, Yoshihiro
N1 - Funding Information:
The experiments were performed at SPring-8 Taiwan beamline BL12XU (under SPring-8 Proposals No. 2018A4257, No. 2018B4251, No. 2019A4266, & No. 2019B4269 corresponding to NSRRC Proposals No. 2018-2-010, No. 2018-3-034, No. 2019-2-030, and No. 2019-3-004). Parts of the computations were carried out at the Supercomputer Center at the Institute for Solid State Physics, the University of Tokyo. Our deepest thanks go to Takaki Uchiyama and Akihisa Takai in Okayama University, and Yoshitaka Ueno and Yasunari Minami in Kwansei-Gakuin University for the help in the experiments. Ritsuko Eguchi in Okayama University kindly supported the sample preparation. We also appreciate the useful comments from Munetaka Taguchi about the pressure-induced change in the spectra, and from Keiichiro Imura in Nagoya University about the estimation of the carrier density in the Hall coefficient measurement. This work has been partly supported by Grants-in-Aid for Scientific Research (KAKENHI Grants No. 18K18736, No. 18K18743, and No. 19H02676) from MEXT and by the Program for Promoting the Enhancement of Research Universities.
Publisher Copyright:
© 2020 American Physical Society.
PY - 2020/10
Y1 - 2020/10
N2 - The pressure-induced change in the electronic structures of the superconductors Bi2Se3 and AgxBi2Se3 has been measured with high-resolution X-ray absorption spectroscopy. As a common feature for these compounds, we find that pressure causes the broadening of the Se 4p band and an energy shift of the Bi 6s band above the Fermi level up to the pressure of the first structural transition. These results, corroborated by density functional theory calculations, correlate with an increase of the carrier density, the disappearance of the band gap, and the emergence of superconductivity. The electronic structure changes significantly at the pressure of the first structural transition, which may be a trigger of the emergence of superconductivity, while above the pressure of the first phase transition it does not change much even around the second phase transition pressure, corresponding to the nearly constant Tc above the pressure of the second structural transition.
AB - The pressure-induced change in the electronic structures of the superconductors Bi2Se3 and AgxBi2Se3 has been measured with high-resolution X-ray absorption spectroscopy. As a common feature for these compounds, we find that pressure causes the broadening of the Se 4p band and an energy shift of the Bi 6s band above the Fermi level up to the pressure of the first structural transition. These results, corroborated by density functional theory calculations, correlate with an increase of the carrier density, the disappearance of the band gap, and the emergence of superconductivity. The electronic structure changes significantly at the pressure of the first structural transition, which may be a trigger of the emergence of superconductivity, while above the pressure of the first phase transition it does not change much even around the second phase transition pressure, corresponding to the nearly constant Tc above the pressure of the second structural transition.
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U2 - 10.1103/PhysRevB.102.155118
DO - 10.1103/PhysRevB.102.155118
M3 - Article
AN - SCOPUS:85094325758
SN - 2469-9950
VL - 102
JO - Physical Review B
JF - Physical Review B
IS - 15
M1 - 155118
ER -