Point nodes persisting far beyond Tc in Bi2212.
Point nodes persisting far beyond Tc in Bi2212.
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DOI：
10.1038/ncomms8699
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发表时间：
2015-07-09
影响因子：
16.6
通讯作者：
Shin S
中科院分区：
文献类型：
--
作者：
Kondo T;Malaeb W;Ishida Y;Sasagawa T;Sakamoto H;Takeuchi T;Tohyama T;Shin S
与负结态的复杂特征不同，铜氧化物的配对能隙是在结区得到的，因此它是研究超导机制的关键。最大的问题之一是，作为d波配对标志的点结态是否像BCS型超导体那样在Tc处坍塌，或者它在Tc以上存活下来，变成预成型的对态。这个问题的一个困难是节点间隙的大小很小，这一直阻碍着实验工作者解决它。在这里，我们使用能够超高能量分辨率的激光ARPES，并检测出Bi 2212中远超过Tc的点节点。通过跟踪光谱的温度演化，我们揭示了超导性发生时，对破碎率被抑制小于冷却时的单粒子散射率，这决定了在铜酸盐的Tc值。 高T c铜酸盐的配对间隙预计将在转变温度下关闭，类似于传统超导体的情况。在这里，作者进行ARPES测量Bi 2212，并揭示了一个点结间隙形成超过T c，其特征在于在三个参数。
In contrast to a complex feature of antinodal state, suffering from competing orders, the pairing gap of cuprates is obtained in the nodal region, which therefore holds the key to the superconducting mechanism. One of the biggest question is whether the point nodal state as a hallmark of d-wave pairing collapses at Tc like the BCS-type superconductors, or it instead survives above Tc turning into the preformed pair state. A difficulty in this issue comes from the small magnitude of the nodal gap, which has been preventing experimentalists from solving it. Here we use a laser ARPES capable of ultrahigh-energy resolution, and detect the point nodes surviving far beyond Tc in Bi2212. By tracking the temperature evolution of spectra, we reveal that the superconductivity occurs when the pair-breaking rate is suppressed smaller than the single-particle scattering rate on cooling, which governs the value of Tc in cuprates. The pairing gap of the high-T c cuprates has been expected to close at the transition temperature, similarly to the case of conventional superconductors. Here the authors perform ARPES measurements on Bi2212, and reveal a point nodal gap formation beyond T c, characterized in terms of three parameters.