近日，斯洛文尼亚斯蒂芬研究所的Jure Kokalj及其研究团队取得一项新进展。经过不懈努力，他们揭示了高T_c铜离子YBa₂Cu₃O_6+x正常态下的电子扩散。相关研究成果已于2024年3月12日在国际知名学术期刊《美国科学院院刊》上发表。

据悉，电阻率超越Mott-Ioffe-Regel（MIR）极限的坏金属相在铜超导体中同样存在。最近，科学家通过冷原子和哈伯德模型的计算机模拟，深入研究了其电荷磁化率和电荷扩散常数的特性。然而，由于可靠的模拟通常只能在高于实验条件的温度下进行，关于铜超导体的相关问题仍然悬而未决。

本文采用热传递方法来解决这一问题，从而估算电子扩散，并进一步将其与电阻率相结合，以评估电荷磁化率。文中详细探讨了两种YBa₂Cu₃O_6+x样品的扩散常数和电荷磁化率，随掺杂和温度变化的依赖关系。研究结果显示，在温度高于约200 K的条件下，欠掺杂样品表现出强烈的非相干输运特性，其平均自由程与Mott-Ioffe-Regel极限相对应，且电荷磁化率对电阻率具有显著影响。

附：英文原文

Title: Electronic diffusion in a normal state of high-Tc cuprate YBa₂Cu₃O_6+x

Author: Kokalj, Jure

Issue&Volume: 2024-3-12

Abstract: The bad metallic phase with resistivity above the Mott–Ioffe–Regel (MIR) limit, which appears also in cuprate superconductors, was recently understood by cold atom and computer simulations of the Hubbard model via charge susceptibility and charge diffusion constant. However, since reliable simulations can be typically done only at temperatures above the experimental temperatures, the question for cuprate superconductors is still open. This paper addresses this question by resorting to heat transport, which allows for the estimate of electronic diffusion and it further combines it with the resistivity to estimate the charge susceptibility. The doping and temperature dependencies of diffusion constant and charge susceptibilities are shown and discussed for two samples of YBa₂Cu₃O_6+x. Results indicate strongly incoherent transport, mean free path corresponding to the MIR limit for the underdoped sample at temperatures above ~200 K and significant effect of the charge susceptibility on the resistivity.

DOI: 10.1073/pnas.2322670121

Source: https://www.pnas.org/doi/abs/10.1073/pnas.2322670121