Felix Bloch Institute for Solid State Physics, Leipzig University 04103, Leipzig, Germany.
Walther Meissner Institut, Bayerische Akademie der Wissenschaften 85748, Garching, Germany.
Proc Natl Acad Sci U S A. 2023 Jan 10;120(2):e2215458120. doi: 10.1073/pnas.2215458120. Epub 2023 Jan 6.
High-temperature superconducting cuprates respond to doping with a dome-like dependence of their critical temperature (). But the family-specific maximum can be surpassed by application of pressure, a compelling observation known for decades. We investigate the phenomenon with high-pressure anvil cell NMR and measure the charge content at planar Cu and O, and with it the doping of the ubiquitous CuO plane with atomic-scale resolution. We find that pressure increases the overall hole doping, as widely assumed, but when it enhances above what can be achieved by doping, pressure leads to a hole redistribution favoring planar O. This is similar to the observation that the family-specific maximum is higher for materials where the hole content at planar O is higher at the expense of that at planar Cu. The latter reflects dependence of the maximum on the Cu-O bond covalence and the charge-transfer gap. The results presented here indicate that the pressure-induced enhancement of the maximum points to the same mechanism.
高温超导铜酸盐对掺杂的响应表现为其临界温度（）的穹顶状依赖关系。但是，几十年来人们已经知道，通过施加压力可以超过特定家族的最大 值。我们使用高压砧细胞 NMR 研究了这一现象，并测量了平面 Cu 和 O 的电荷含量，从而以原子级分辨率测量了普遍存在的 CuO 平面的掺杂情况。我们发现，压力像人们普遍认为的那样增加了整体空穴掺杂，但当它增强到超过掺杂所能达到的值时，压力会导致空穴重新分布，有利于平面 O。这类似于这样的观察结果，即在平面 O 的空穴含量更高而平面 Cu 的空穴含量更低的材料中，特定家族的最大 值更高。后者反映了最大 值对 Cu-O 键共价性和电荷转移间隙的依赖性。这里呈现的结果表明，压力诱导的最大 值增强指向相同的机制。
