近日，中国科学院物理研究所的周兴江研究员及其研究小组取得一项新进展。经过不懈努力，他们揭示了三层铜中高超导临界温度的电子起源。相关研究成果已于2023年9月14日在国际知名学术期刊《自然—物理学》上发表。
据悉，高温铜超导体中的超导转变温度(Tc)取决于结构单元中CuO2平面的数量，三层体系中实现了最高的Tc。三层超导体也表现出不寻常的相图，其中Tc在过掺杂区域大致恒定，这与其他铜超导体中通常观察到的降低形成鲜明对比。这两种效应的机制尚不清楚。
该研究团队报道了Bi2Sr2Ca2Cu3O10+δ超导体电子结构特征，这有助于解释上述问题。研究人员的角度分辨光谱学测量显示了三层波段的分裂，这使他们能够构建一个三层相互作用模型，该模型可以有效地描述数据。这反过来又证明了最大Tc的电子来源及其在过掺杂区域的持久性。这些结果与复合图像在质量上一致，该图像在不同掺杂水平的耦合平面阵列中实现了高Tc，因此，高配对强度来自于未掺杂平面，而大的相刚度来自于最佳或过掺杂平面。
附：英文原文
Title: Electronic origin of high superconducting critical temperature in trilayer cuprates
Author: Luo, Xiangyu, Chen, Hao, Li, Yinghao, Gao, Qiang, Yin, Chaohui, Yan, Hongtao, Miao, Taimin, Luo, Hailan, Shu, Yingjie, Chen, Yiwen, Lin, Chengtian, Zhang, Shenjin, Wang, Zhimin, Zhang, Fengfeng, Yang, Feng, Peng, Qinjun, Liu, Guodong, Zhao, Lin, Xu, Zuyan, Xiang, Tao, Zhou, X. J.
Issue&Volume: 2023-09-14
Abstract: In high-temperature cuprate superconductors, the superconducting transition temperature (Tc) depends on the number of CuO2 planes in the structural unit and the maximum Tc is realized in the trilayer system. Trilayer superconductors also exhibit an unusual phase diagram where Tc is roughly constant in the overdoped region, which is in contrast to the decrease usually found in other cuprate superconductors. The mechanism for these two effects remains unclear. Here we report features in the electronic structure of Bi2Sr2Ca2Cu3O10+δ superconductor that helps to explain this issue. Our angle-resolved photoemission spectroscopy measurements show the splitting of bands from the three layers, and this allows us to parameterize a three-layer interaction model that effectively describes the data. This, in turn, demonstrates the electronic origin of the maximum Tc and its persistence in the overdoped region. These results are qualitatively consistent with a composite picture where a high Tc is realized in an array of coupled planes with different doping levels such that a high pairing strength is derived from the underdoped planes, whereas a large phase stiffness comes from the optimally or overdoped ones.
DOI: 10.1038/s41567-023-02206-0
Source: https://www.nature.com/articles/s41567-023-02206-0