Direct observation of competition between superconductivity and charge density wave order in YBa2Cu3O6.67
Direct observation of competition between superconductivity and charge density wave order in YBa2Cu3O6.67
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DOI：
10.1038/nphys2456
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发表时间：
2012-12-01
期刊：
影响因子：
19.6
通讯作者：
Hayden, S. M.
中科院分区：
文献类型：
--
作者：
Chang, J.;Blackburn, E.;Hayden, S. M.
超导性通常出现在对称破缺的基态附近或与之竞争，如反铁磁性或电荷密度波（CDW）。铜族中的许多材料，包括高转变温度（高t -c）超导体，显示自旋和电荷密度波序（5-7）。因此，一个基本的问题是，这些有序态在多大程度上存在于接近超导最佳的组合物中。本文利用高能x射线衍射证明，在超导YBa2Cu3O6.67 （T-c = 67 K）的正常状态下，CDW在零场产生。该样品具有每铜掺杂0.12个孔和有序的氧链上层结构(8)。在T-c以下，磁场抑制了超导性，增强了CDW。因此，在这种典型的高t -c材料中，CDW和超导性是具有相似能量尺度的竞争级，并且高t -c超导性是由预先存在的CDW环境形成的。我们的研究结果为小费米表面口袋的形成提供了一种机制，这解释了这种材料在欠掺杂时的负霍尔和塞贝克效应（10,11）和“T-c平台”（12）。
Superconductivity often emerges in the proximity of, or in competition with, symmetry-breaking ground states such as antiferromagnetism or charge density waves(1-5) (CDW). A number of materials in the cuprate family, which includes the high transition-temperature (high-T-c) superconductors, show spin and charge density wave order(5-7). Thus a fundamental question is to what extent do these ordered states exist for compositions close to optimal for superconductivity. Here we use high-energy X-ray diffraction to show that a CDW develops at zero field in the normal state of superconducting YBa2Cu3O6.67 (T-c = 67 K). This sample has a hole doping of 0.12 per copper and a well-ordered oxygen chain superstructure(8). Below T-c, the application of a magnetic field suppresses superconductivity and enhances the CDW. Hence, the CDW and superconductivity in this typical high-T-c material are competing orders with similar energy scales, and the high-T-c superconductivity forms from a pre-existing CDW environment. Our results provide a mechanism for the formation of small Fermi surface pockets9, which explain the negative Hall and Seebeck effects(10,11) and the `T-c plateau'(12) in this material when underdoped.