[论文解读] Connection between charge-density-wave order and charge transport in the cuprate superconductors

Wojciech Tabiś, Yilei Li+18 more|arXiv (Cornell University)|Apr 30, 2014

Physics of Superconductivity and Magnetism参考文献 30被引用 135

一句话总结

本研究探讨了具有高结构对称性和费米液体行为的铜氧化物HgBa2CuO4+δ（Hg1201）中电荷密度波（CDW）序与电荷输运之间的相互作用。利用共振X射线散射，作者在约200 K以下观测到短程CDW关联，其与费米液体输运共存，表明CDW序可能驱动了该材料中观测到的低温量子振荡响应。

ABSTRACT

Charge-density-wave (CDW) correlations within the quintessential CuO$_2$ planes have been argued to either cause [1] or compete with [2] the superconductivity in the cuprates, and they might furthermore drive the Fermi-surface reconstruction in high magnetic fields implied by quantum oscillation (QO) experiments for YBa$_2$Cu$_3$O$_{6+δ}$ (YBCO) [3] and HgBa$_2$CuO$_{4+δ}$ (Hg1201) [4]. Consequently, the observation of bulk CDW order in YBCO was a significant development [5,6,7]. Hg1201 features particularly high structural symmetry and recently has been demonstrated to exhibit Fermi-liquid charge transport in the relevant temperature-doping range of the phase diagram, whereas for YBCO and other cuprates this underlying property of the CuO$_2$ planes is partially or fully masked [8-10]. It therefore is imperative to establish if the pristine transport behavior of Hg1201 is compatible with CDW order. Here we investigate Hg1201 ($T_c$ = 72 K) via bulk Cu L-edge resonant X-ray scattering. We indeed observe CDW correlations in the absence of a magnetic field, although the correlations and competition with superconductivity are weaker than in YBCO. Interestingly, at the measured hole-doping level, both the short-range CDW and Fermi-liquid transport appear below the same temperature of about 200 K. Our result points to a unifying picture in which the CDW formation is preceded at the higher pseudogap temperature by $q$ = 0 magnetic order [11,12] and the build-up of significant dynamic antiferromagnetic correlations [13]. Furthermore, the smaller CDW modulation wave vector observed for Hg1201 is consistent with the larger electron pocket implied by both QO [4] and Hall-effect [14] measurements, which suggests that CDW correlations are indeed responsible for the low-temperature QO phenomenon.

研究动机与目标

• 确定本征费米液体输运在Hg1201中是否与电荷密度波（CDW）序共存。
• 研究具有高结构对称性和最小电子非均匀性的铜氧化物中CDW关联与电荷输运之间的关系。
• 澄清CDW序是否能够解释在Hg1201和YBCO中观测到的低温量子振荡响应。

提出的方法

• 采用Cu L边的共振X射线散射探测Hg1201中的电荷密度波（CDW）序。
• 在零磁场下进行测量，以隔离本征CDW关联。
• 研究聚焦于接近最佳掺杂的空穴掺杂区域，该区域预期呈现费米液体输运行为。
• 数据分析将CDW关联强度及其温度演化与输运性质进行比较。
• 结果在更广泛的铜氧化物相图背景下进行阐释，特别是关于赝能隙和反铁磁序方面。

实验结果

研究问题

• RQ1 电荷密度波（CDW）序是否与Hg1201中的费米液体输运共存？
• RQ2 Hg1201中的CDW序是否足够强且具有足够关联性，以解释低温量子振荡响应？
• RQ3 Hg1201中的CDW波矢与YBCO相比如何，这对费米面重构有何含义？
• RQ4 在Hg1201中，CDW序的出现是否先于$ q=0 $磁序或动态反铁磁关联？
• RQ5 在Hg1201中观测到的CDW关联是否能够解释从量子振荡和霍尔效应测量推断出的电子口袋尺寸？

主要发现

• 在无外磁场条件下观测到Hg1201中存在短程电荷密度波（CDW）关联，证实其为本征性质。
• CDW序在约200 K以下出现，与费米液体输运行为的出现同步。
• Hg1201中的CDW调制波矢小于YBCO中的值，与从量子振荡和霍尔效应测量推断出的较大电子口袋尺寸一致。
• 在~200 K以下CDW序与费米液体输运的共存表明，CDW形成可能与低温量子振荡响应存在统一机制。
• 结果表明CDW序可能是量子振荡实验中观测到的费米面重构的原因，支持量子振荡现象源于CDW驱动的机制。