近日，美国SLAC国家加速器实验室的Joshua J. Turner&Lingjia Shen及其研究团队取得一项新进展。他们通过准静态晶格涨落理解超导性和电荷密度波的相互作用。相关研究成果已于2024年12月4日在国际知名学术期刊《美国科学院院刊》上发表。

本研究通过X射线光子相关光谱法，在准静态时间尺度（数千秒）上测量欠掺杂YBa₂Cu₃O_6+y中细微的晶格涨落，研究人员发现该方法对超导性和电荷密度波（CDW）均敏感。当接近超导转变温度T_c≈65K时，原子晶格展现出显著更快的弛豫动力学。

通过追踪动量依赖性，研究表明，在T_c以上及存在CDW态的情况下，中间散射函数几乎单调地与原子离开其平均位置的弛豫距离成比例，而在其他温度下，这种特殊趋势则发生逆转。这些观测结果与由局部应变稳定的初始CDW相一致。本研究为理解由于载流子掺杂而固有无序的铜酸盐中电子物理的关键角色——原子弛豫涨落，提供了见解。

据悉，在非传统超导体中，电荷与晶格自由度之间的耦合可以表现为相互缠绕的有序物质相。在铜酸盐家族中，短程电荷涨落可以聚集成较长程的电荷密度波（CDW）序，这种序被认为与超导性相互交织，但其相互作用的本质仍知之甚少。

附：英文原文

Title: Understanding the superconductivity and charge density wave interaction through quasi-static lattice fluctuations

Author: Porter, Zach, Shen, Lingjia, Plumley, Rajan, Burdet, Nicolas G., Petsch, Alexander N., Wen, Jiajia, Drucker, Nathan C., Peng, Cheng, Chen, Xiaoqian M., Fluerasu, Andrei, Blackburn, Elizabeth, Coslovich, Giacomo, Hawthorn, David G., Turner, Joshua J.

Issue&Volume: 2024-12-4

Abstract: In unconventional superconductors, coupled charge and lattice degrees of freedom can manifest in ordered phases of matter that are intertwined. In the cuprate family, fluctuating short-range charge correlations can coalesce into a longer-range charge density wave (CDW) order which is thought to intertwine with superconductivity, yet the nature of the interaction is still poorly understood. Here, by measuring subtle lattice fluctuations in underdoped YBa₂Cu₃O_6+y on quasi-static timescales (thousands of seconds) through X-ray photon correlation spectroscopy, we report sensitivity to both superconductivity and CDW. The atomic lattice shows remarkably faster relaxational dynamics upon approaching the superconducting transition at T_c ≈ 65 K. By tracking the momentum dependence, we show that the intermediate scattering function almost monotonically scales with the relaxation distance of atoms away from their average positions above T_c and in the presence of the CDW state, while this peculiar trend is reversed for other temperatures. These observations are consistent with an incipient CDW stabilized by local strain. This work provides insights into the crucial role of relaxational atomic fluctuations for understanding the electronic physics cuprates, which are inherently disordered due to carrier doping.

DOI: 10.1073/pnas.2412182121

Source: https://www.pnas.org/doi/abs/10.1073/pnas.2412182121