Absence of a BCS-BEC crossover in the cuprate superconductors
Absence of a BCS-BEC crossover in the cuprate superconductors
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DOI：
10.1038/s41535-023-00550-1
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发表时间：
2022-10
影响因子：
5.7
通讯作者：
J. Sous;Yu He;S. Kivelson
中科院分区：
文献类型：
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作者：
J. Sous;Yu He;S. Kivelson
我们研究了巴丁-库珀-施里弗 (BCS) 与玻色-爱因斯坦凝聚 (BEC) 交叉理论的关键方面，重点关注化学势 μ 的温度依赖性。我们确定了一种根据角分辨光发射数据（沿“节点”方向）确定铜酸盐高温超导体中 μ 变化的准确方法，并表明，在远低于超导转变温度 Tc 到高几倍的温度范围内，μ 的变化不到费米能量的百分之几。这明确地表明，这些材料不仅总是位于交叉点的 BCS 侧（这是 d 波情况下的相变），而且远离交叉点（化学势接近能带底部）。
We examine key aspects of the theory of the Bardeen–Cooper–Schrieffer (BCS) to Bose–Einstein condensation (BEC) crossover, focusing on the temperature dependence of the chemical potential,μ. We identify an accurate method of determining the change ofμin the cuprate high temperature superconductors from angle-resolved-photoemission data (along the ‘nodal’ direction), and show thatμvaries by less than a few percent of the Fermi energy over a range of temperatures from far below to several times above the superconducting transition temperature,Tc. This shows, unambiguously, that not only are these materials always on the BCS side of the crossover (which is a phase transition in thed-wave case), but are nowhere near the point of the crossover (where the chemical potential approaches the band bottom).