The influence of Mott physics on the doping–temperature phase diagram of copper oxides represents a major issue that is the subject of intense theoretical and experimental efforts. Here, we investigate the ultrafast electron dynamics in prototypical single-layer Bi-based cuprates at the energy scale of the O-2p Cu-3d charge-transfer (CT) process. We demonstrate a clear evolution of the CT excitations from incoherent and localized, as in a Mott insulator, to coherent and delocalized, as in a conventional metal. This reorganization of the high-energy degrees of freedom occurs at the critical doping p_cr ≈ 0.16 irrespective of the temperature, and it can be well described by dynamical mean-field theory calculations. We argue that the onset of low-temperature charge instabilities is the low-energy manifestation of the underlying Mottness that characterizes the p < p_cr region of the phase diagram. This discovery sets a new framework for theories of charge order and low-temperature phases in underdoped copper oxides.

中文翻译：

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有限掺杂中的摩尔数和铜酸盐中的电荷不稳定性

莫特物理学对铜氧化物的掺杂-温度相图的影响代表了一个重大问题，这是大量理论和实验工作的主题。在这里，我们研究了在O-2 p Cu-3 d电荷转移（CT）过程的能量尺度下，典型的单层Bi基铜酸盐的超快电子动力学。我们证明了CT激励从不相干和局域化（如在Mott绝缘子中）到相干和局域化（如常规金属中）的清晰演变。高能量的自由度的此重组发生在临界掺杂p _CR ≈不论温度如何，都为0.16，可以通过动态平均场理论计算很好地描述它。我们认为，低温电荷不稳定性的开始是潜在莫特性的低能表现，它表征了相图的p < p _cr区域。这一发现为掺杂不足的氧化铜中的电荷有序和低温相理论奠定了新的框架。