Fujiwara N, Môri N, Uwatoko Y, Matsumoto T, Motoyama N, Uchida S. Superconductivity of the Sr2Ca12Cu24O41 spin-ladder system: are the superconducting pairing and the spin-gap formation of the same origin?
PHYSICAL REVIEW LETTERS 2003;
90:137001. [PMID:
12689316 DOI:
10.1103/physrevlett.90.137001]
[Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2002] [Indexed: 05/24/2023]
Abstract
Pressure-induced superconductivity in a spin-ladder cuprate Sr2Ca12Cu24O41 has not been studied on a microscopic level thus far although the superconductivity was already discovered in 1996. We have improved the high-pressure technique using a large high-quality crystal, and succeeded in studying the superconductivity using 63Cu nuclear magnetic resonance. We found that the anomalous metallic state reflecting the spin-ladder structure is realized and the superconductivity possesses an s-wave-like character in the meaning that a finite gap exists in the quasiparticle excitation: At a pressure of 3.5 GPa, we observed two excitation modes in the normal state from the relaxation rate T-11. One gives rise to an activation-type component in T-11, and the other T-linear component linking directly with the superconductivity. This gapless mode likely arises from free motion of holon-spinon bound states appearing by hole doping, and the pairing of them likely causes the superconductivity.
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