Physic seminar_

 Talk by Prof. E.M. (Ted) Forgan, School of Physics & Astronomy, University of Birmingham, U.K.

YBCO continues to surprise: recent discoveries of the competition between charge density wave order and superconductivity

The YBa2Cu3Oy family of high temperature superconductors (HTS) is one of the most well-studied materials known. Despite this, superconductivity in YBCO and other HTS has proved frustratingly hard to understand, and it appears that doped antiferromagnets have other instabilities apart from superconductivity. An example of this is “stripes”- coupled charge and spin order which is observed in some HTS and related compounds [1]. However, we have shown in our recent X-ray diffraction measurements that stripes are not a generic property of cuprates. Instead, we and others have found an incommensurate charge density wave (CDW) in YBa2Cu3Oy [2-5]. This coexists with superconductivity, but competes directly with it and the CDW is enhanced when superconductivity is suppressed by magnetic field. These observations raise fascinating questions about what may be limiting the maximum Tc for HTS, the link between the CDW and the electrons in the CuO2 layers and whether the superconducting dome straddles a Quantum Critical Point.

References

[1] S. A. Kivelson, I. P. Bindloss, V. Oganesyan, J. M. Tranquada, A. Kapitulnik, and C. Howald, Rev. Mod. Phys. 75, 1201 (2003).

[2] 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, Nat. Phys. 8, 871 (2012).

[3] G. Ghiringhelli, M. Le Tacon, M. Minola, S. Blanco-Canosa, C. Mazzoli, N. B. Brookes, G. M. De Luca, A. Frano, D. G. Hawthorn, F. He, T. Loew, M. Moretti Sala, D. C. Peets, M. Salluzzo, E. Schierle, R. Sutarto, G. A. Sawatzky, E. Weschke, B. Keimer, L. Braicovich Science 337, 821 (2012).

[4] E. Blackburn, J. Chang, M. Hücker, A. T. Holmes, N. B. Christensen, Ruixing Liang, D. A. Bonn, W. N. Hardy, U. Rütt, O. Gutowski, M. v. Zimmermann, E. M. Forgan, and S. M. Hayden, Phys. Rev. Lett. 110, 137004 (2013)

[5] S. Blanco-Canosa et al., arXiv:1212.5580

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