标题： 均匀高温超导体中电荷有序和赝能隙的同时出现 显示英文标题

标题： Coincident onset of charge order and pseudogap in a homogeneous high-temperature superconductor

摘要： 理解铜氧化物中的高温超导性需要了解它所演变的金属态，特别是低载流子密度下显著影响电子性质的伪能隙。 一个关键问题是化学无序的影响，这种无序普遍存在但极其难以建模。 利用共振 X 射线散射，我们在化学成分精确的 YBa$_2$Cu$_4$O$_8$ ($T_c$ = 80 K) 中识别出二维电荷有序现象，该材料几乎不存在化学无序。 电荷有序的幅度表现出凹形温度依赖性，并在 $T^*$ = 200 K 时突然消失，这是先前通过光谱学确定的明显伪能隙的起始温度，表明这些现象之间存在因果关系。 因此，其他铜氧化物中电荷有序的逐渐出现很可能是由于由化学取代引起的无序导致的电荷有序温度分布不均匀。 伪能隙与由无序引起的电荷载流子逐步冻结之间的关系仍然是研究高-$T_c$ 超导体的核心问题。 显示英文摘要

摘要： Understanding high-temperature superconductivity in cuprates requires knowledge of the metallic phase it evolves from, particularly the pseudogap profoundly affecting the electronic properties at low carrier densities. A key question is the influence of chemical disorder, which is ubiquitous but exceedingly difficult to model. Using resonant x-ray scattering, we identified two-dimensional charge order in stoichiometric YBa$_2$Cu$_4$O$_8$ ($T_c$ = 80 K), which is nearly free of chemical disorder. The charge order amplitude shows a concave temperature dependence and vanishes sharply at $T^*$ = 200 K, the onset of a prominent pseudogap previously determined by spectroscopy, suggesting a causal link between these phenomena. The gradual onset of charge order in other cuprates is thus likely attributable to an inhomogeneous distribution of charge ordering temperatures due to disorder induced by chemical substitution. The relationship between the pseudogap and the disorder-induced gradual freeze-out of charge carriers remains a central issue in research on high-$T_c$ superconductors.