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Direct observation of competition between superconductivity and charge density wave order in YBa2Cu3O6.67

2012; Nature Portfolio; Volume: 8; Issue: 12 Linguagem: Inglês

10.1038/nphys2456

1745-2481

J. Chang, E. Blackburn, A. T. Holmes, N. B. Christensen, J. Larsen, J. Mesot, Ruixing Liang, D. A. Bonn, W. N. Hardy, A. Watenphul, M. v. Zimmermann, E. M. Forgan, S. M. Hayden,

Magnetic and transport properties of perovskites and related materials

X-ray diffraction experiments reveal that spatial charge ordering occurs in the pseudogap state of YBa2Cu3O6.67. Moreover, this charge ordered state competes with high-temperature superconductivity, and their relative strengths can be tuned using a magnetic field. Superconductivity often emerges in the proximity of, or in competition with, symmetry-breaking ground states such as antiferromagnetism or charge density waves1,2,3,4,5 (CDW). A number of materials in the cuprate family, which includes the high transition-temperature (high-Tc) superconductors, show spin and charge density wave order5,6,7. 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 (Tc = 67 K). This sample has a hole doping of 0.12 per copper and a well-ordered oxygen chain superstructure8. Below Tc, the application of a magnetic field suppresses superconductivity and enhances the CDW. Hence, the CDW and superconductivity in this typical high-Tc material are competing orders with similar energy scales, and the high-Tc 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 effects10,11 and the ‘Tc plateau’12 in this material when underdoped.