Superconductivity of the Sr2Ca12Cu24O41 spin-ladder system:: Are the superconducting pairing and the spin-gap formation of the same origin? -: art. no. 137001
Superconductivity of the Sr2Ca12Cu24O41 spin-ladder system:: Are the superconducting pairing and the spin-gap formation of the same origin? -: art. no. 137001
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DOI：
10.1103/physrevlett.90.137001
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发表时间：
2003-04-04
影响因子：
8.6
通讯作者：
Uchida, S
中科院分区：
文献类型：
--
作者：
Fujiwara, N;Môri, N;Uchida, S
尽管1996年已经发现了Sr 2Ca 12 Cu 24 O 41的超导电性，但到目前为止，还没有在微观水平上研究过它的压力诱导超导电性。我们改进了高压技术，使用大的高质量晶体，并成功地研究了超导性，使用Cu-63核磁共振。我们发现，超导电性具有类似s波的特征，即在准粒子激发中存在有限能隙。在3.5GPa压力下，从弛豫速率T-1（-1）可以观察到正常态下的两个激发模。一个是T-1（-1）中的激活型分量，另一个是T-线性分量，它与超导性直接相关。这种无带隙模式很可能是由于空穴掺杂而出现的空穴-自旋束缚态的自由运动，它们的配对可能导致超导性。
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 Cu-63 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-1(-1). One gives rise to an activation-type component in T-1(-1), 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.