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arXiv 0902.1342cond-mat.supr-con
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铜氧化物中赝能隙与高温超导性竞争的直接证据

Direct evidence for a competition between the pseudogap and high temperature superconductivity in the cuprates

Takeshi Kondo, Rustem Khasanov, Tsunehiro Takeuchi, Joerg Schmalian, Adam Kaminski

摘要:

对隙和相干性是超导性的两个标志。在经典的BCS超导体中,它们在Tc同时建立。然而,在铜酸盐中,能隙(赝能隙)在Tc以上延伸。这个能隙的起源是高温超导的中心问题之一。最近的实验证据表明,赝能隙和超导能隙与不同的能量尺度有关。然而,尚不清楚它们是独立共存还是相互竞争。为了理解铜氧化物的物理性质和改善其超导性能,确定赝能隙是高温超导电性的朋友还是敌人至关重要。在这里,我们报告的证据,从角度分辨光电子能谱(ARPES)的赝隙和高温超导代表两个竞争的订单。我们发现,有一个直接的相关性之间的损失,在低能量谱的重量,由于pseudogap和成对电子的相干分数的减少。因此,赝能隙通过耗尽在超导能隙最大的动量空间区域中可用于配对的谱权重来与超导性竞争。这导致了一个非常不寻常的状态,在欠掺杂的铜氧化物,其中只有部分的费米表面发展的连贯性。

英文摘要:

A pairing gap and coherence are the two hallmarks of superconductivity. In a classical BCS superconductor they are established simultaneously at Tc. In the cuprates, however, an energy gap (pseudogap) extends above Tc. The origin of this gap is one of the central issues in high temperature superconductivity. Recent experimental evidence demonstrates that the pseudogap and the superconducting gap are associated with different energy scales. It is however not clear whether they coexist independently or compete. In order to understand the physics of cuprates and improve their superconducting properties it is vital to determine whether the pseudogap is friend or foe of high temperature supercondctivity. Here we report evidence from angle resolved photoemission spectroscopy (ARPES) that the pseudogap and high temperature superconductivity represent two competing orders. We find that there is a direct correlation between a loss in the low energy spectral weight due to the pseudogap and a decrease of the coherent fraction of paired electrons. Therefore, the pseudogap competes with the superconductivity by depleting the spectral weight available for pairing in the region of momentum space where the superconducting gap is largest. This leads to a very unusual state in the underdoped cuprates, where only part of the Fermi surface develops coherence.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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