Ishida Y, Saitoh T, Mochiku T, Nakane T, Hirata K, Shin S
ISSP, University of Tokyo, Kashiwa-no-ha, Kashiwa, Chiba 277-8581, Japan.
National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, Japan.
Sci Rep. 2016 Jan 5;6:18747. doi: 10.1038/srep18747.
In a conventional framework, superconductivity is lost at a critical temperature (Tc) because, at higher temperatures, gluing bosons can no longer bind two electrons into a Cooper pair. In high-Tc cuprates, it is still unknown how superconductivity vanishes at Tc. We provide evidence that the so-called ≲ 70-meV kink bosons that dress the quasi-particle excitations are playing a key role in the loss of superconductivity in a cuprate. We irradiated a 170-fs laser pulse on Bi2Sr2CaCu2O(8+δ) and monitored the responses of the superconducting gap and dressed quasi-particles by time- and angle-resolved photoemission spectroscopy. We observe an ultrafast loss of superconducting gap near the d-wave node, or light-induced Fermi arcs, which is accompanied by spectral broadenings and weight redistributions occurring within the kink binding energy. We discuss that the underlying mechanism of the spectral broadening that induce the Fermi arc is the undressing of quasi-particles from the kink bosons. The loss mechanism is beyond the conventional framework, and can accept the unconventional phenomena such as the signatures of Cooper pairs remaining at temperatures above Tc.
在传统框架中，超导性在临界温度（Tc）时会消失，因为在较高温度下，胶合玻色子不再能将两个电子束缚成一个库珀对。在高温铜酸盐中，超导性在Tc时如何消失仍然未知。我们提供证据表明，所谓的≲70毫电子伏特扭结玻色子（它修饰准粒子激发）在铜酸盐超导性的丧失中起着关键作用。我们用170飞秒激光脉冲照射Bi2Sr2CaCu2O(8+δ)，并通过时间分辨和角分辨光电子能谱监测超导能隙和修饰后的准粒子的响应。我们观察到在d波节点附近或光致费米弧处超导能隙的超快丧失，这伴随着在扭结结合能范围内发生的光谱展宽和权重重新分布。我们讨论了诱导费米弧的光谱展宽的潜在机制是准粒子从扭结玻色子上的解束缚。这种丧失机制超出了传统框架，并且可以接受诸如在高于Tc的温度下库珀对的特征等非传统现象。
