High-resolution photoemission study of low- Tc superconductors: Phonon-induced electronic structures in low- Tc superconductors and comparison with the results of high- Tc cuprates

• Published in: Physica. C, Superconductivity Superconductivity, 2002-10, Vol.378, p.97-101
• Main Authors: Yokoya, T., Chainani, A., Kiss, T., Shin, S., Hirata, K., Kameda, N., Tamegai, T., Nishio, T., Uwe, H.
• Format: Article
• Language: English
• Subjects: Photoemission spectroscopy; Pseudogap; Superconducting gap
• ISSN: 0921-4534; 1873-2143
• DOI: 10.1016/S0921-4534(02)01389-8

Recent advances in the energy resolution and cryogenic techniques used in photoemission spectroscopy have enabled us to directly observe the superconducting electronic structure of superconductors with a relatively lower transition temperature (low- T c). In this paper, we report photoemission results on low- T c superconductors measured with an ultrahigh-resolution low-temperature photoemission spectrometer. The result of Nb 3Al exhibits a superconducting gap and a phonon-induced peak–dip–hump structure characteristic of the strong-coupling superconducting spectral function. From measurements of Ba 0.67K 0.33BiO 3, we observe isotropic s-wave superconducting gap opening below T c as well as depletion of intensity near the Fermi level above T c, which can be attributed to a phonon-induced pseudogap. We will compare these photoemission results with those of high- T c superconductors.