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Seo YI, Choi WJ, Kimura SI, Kwon YS. Evidence for a preformed Cooper pair model in the pseudogap spectra of a Ca 10(Pt 4As 8)(Fe 2As 2) 5 single crystal with a nodal superconducting gap. Sci Rep 2019; 9:3987. [PMID: 30850717 PMCID: PMC6408529 DOI: 10.1038/s41598-019-40528-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Accepted: 02/14/2019] [Indexed: 11/28/2022] Open
Abstract
For high-Tc superconductors, clarifying the role and origin of the pseudogap is essential for understanding the pairing mechanism. Among the various models describing the pseudogap, the preformed Cooper pair model is a potential candidate. Therefore, we present experimental evidence for the preformed Cooper pair model by studying the pseudogap spectrum observed in the optical conductivity of a Ca10(Pt4As8)(Fe2As2)5 (Tc = 34.6 K) single crystal. We observed a clear pseudogap structure in the optical conductivity and observed its temperature dependence. In the superconducting (SC) state, one SC gap with a gap size of Δ = 26 cm−1, a scattering rate of 1/τ = 360 cm−1 and a low-frequency extra Drude component were observed. Spectral weight analysis revealed that the SC gap and pseudogap are formed from the same Drude band. This means that the pseudogap is a gap structure observed as a result of a continuous temperature evolution of the SC gap observed below Tc. This provides clear experimental evidence for the preformed Cooper pair model.
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Affiliation(s)
- Y I Seo
- Department of Emerging Materials Science, DGIST, Daegu, 711-873, Republic of Korea
| | - W J Choi
- Department of Emerging Materials Science, DGIST, Daegu, 711-873, Republic of Korea
| | - Shin-Ichi Kimura
- Graduate School of Frontier Biosciences and Department of Physics, Graduate School of Science, Osaka University, Suita, 565-0871, Japan
| | - Yong Seung Kwon
- Department of Emerging Materials Science, DGIST, Daegu, 711-873, Republic of Korea.
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Kawakami T, Takeda R, Nishihara S, Saito T, Shoji M, Yamada S, Yamanaka S, Kitagawa Y, Okumura M, Yamaguchi K. Symmetry and Broken-Symmetry in Molecular Orbital Descriptions of Unstable Molecules. 3. The Nature of Chemical Bonds of Spin Frustrated Systems. J Phys Chem A 2009; 113:15281-97. [DOI: 10.1021/jp905991r] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- T. Kawakami
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan, Nanomaterial Design Center, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan, and Institute for Protein Research, Osaka University, Suita, Osaka 565-0871, Japan
| | - R. Takeda
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan, Nanomaterial Design Center, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan, and Institute for Protein Research, Osaka University, Suita, Osaka 565-0871, Japan
| | - S. Nishihara
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan, Nanomaterial Design Center, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan, and Institute for Protein Research, Osaka University, Suita, Osaka 565-0871, Japan
| | - T. Saito
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan, Nanomaterial Design Center, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan, and Institute for Protein Research, Osaka University, Suita, Osaka 565-0871, Japan
| | - M. Shoji
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan, Nanomaterial Design Center, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan, and Institute for Protein Research, Osaka University, Suita, Osaka 565-0871, Japan
| | - S. Yamada
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan, Nanomaterial Design Center, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan, and Institute for Protein Research, Osaka University, Suita, Osaka 565-0871, Japan
| | - S. Yamanaka
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan, Nanomaterial Design Center, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan, and Institute for Protein Research, Osaka University, Suita, Osaka 565-0871, Japan
| | - Y. Kitagawa
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan, Nanomaterial Design Center, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan, and Institute for Protein Research, Osaka University, Suita, Osaka 565-0871, Japan
| | - M. Okumura
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan, Nanomaterial Design Center, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan, and Institute for Protein Research, Osaka University, Suita, Osaka 565-0871, Japan
| | - K. Yamaguchi
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan, Nanomaterial Design Center, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan, and Institute for Protein Research, Osaka University, Suita, Osaka 565-0871, Japan
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