Department of Physics, Stanford University, Stanford, CA 94305; and
Laboratoire de Physique Théorique de la Matière Condensée, Université Pierre et Marie Curie, 75252 Paris Cedex 05, France.
Proc Natl Acad Sci U S A. 2014 Jun 3;111(22):7980-5. doi: 10.1073/pnas.1406019111. Epub 2014 May 5.
The cuprate high-temperature superconductors have been the focus of unprecedentedly intense and sustained study not only because of their high superconducting transition temperatures, but also because they represent the most exquisitely investigated examples of highly correlated electronic materials. In particular, the pseudogap regime of the phase diagram exhibits a variety of mysterious emergent behaviors. In the last few years, evidence from NMR and scanning tunneling microscopy (STM) studies, as well as from a new generation of X-ray scattering experiments, has accumulated, indicating that a general tendency to short-range-correlated incommensurate charge density wave (CDW) order is "intertwined" with the superconductivity in this regime. Additionally, transport, STM, neutron-scattering, and optical experiments have produced evidence--not yet entirely understood--of the existence of an associated pattern of long-range-ordered point-group symmetry breaking with an electron-nematic character. We have carried out a theoretical analysis of the Landau-Ginzburg-Wilson effective field theory of a classical incommensurate CDW in the presence of weak quenched disorder. Although the possibilities of a sharp phase transition and long-range CDW order are precluded in such systems, we show that any discrete symmetry-breaking aspect of the charge order--nematicity in the case of the unidirectional (stripe) CDW we consider explicitly--generically survives up to a nonzero critical disorder strength. Such "vestigial order," which is subject to unambiguous macroscopic detection, can serve as an avatar of what would be CDW order in the ideal, zero disorder limit. Various recent experiments in the pseudogap regime of the hole-doped cuprates are readily interpreted in light of these results.
高温超导铜酸盐已经成为了前所未有的强烈和持续研究的焦点，这不仅是因为它们具有高超导转变温度，还因为它们代表了高度关联电子材料中研究得最精细的例子。特别是，相图的赝能隙区域表现出各种神秘的涌现行为。在过去的几年中，来自 NMR 和扫描隧道显微镜 (STM) 研究以及新一代 X 射线散射实验的证据积累表明，一种普遍的短程相关非调谐电荷密度波 (CDW) 有序的趋势与该区域的超导性“交织”在一起。此外，输运、STM、中子散射和光学实验已经产生了证据——尽管尚未完全理解——存在与电子向列特征相关的长程有序点群对称性破缺的模式。我们对存在弱淬火无序的经典非调谐 CDW 的朗道-金兹堡-威尔逊有效场理论进行了理论分析。尽管在这样的系统中排除了尖锐的相变和长程 CDW 有序的可能性，但我们表明，电荷有序的任何离散对称破缺方面——在我们明确考虑的单向（条纹）CDW 的情况下是向列性——在非零临界无序强度下普遍存在。这种“残余有序”受到明确的宏观检测，可以作为在理想、零无序极限下 CDW 有序的代表。最近在掺杂空穴铜酸盐的赝能隙区域进行的各种实验都可以根据这些结果进行解释。
