Berlin 2008 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 33: Symposium: High-Temperature Superconductivity

TT 33.3: Invited Talk

Thursday, February 28, 2008, 14:45–15:15, H 0104

Superconductivity in the Hubbard model and the two gap energy scales in high-temperature superconductors — •Markus Aichhorn¹, Enrico Arrigoni², Michael Potthoff³, Zhong Bing Huang⁴, and Werner Hanke¹ — ¹Institut für Theoretische Physik und Astrophysik, Universität Würzburg — ²Institut für Theoretische Physik und Computational Physics, Technische Universität Graz — ³I. Institut für Theoretische Physik, Universität Hamburg — ⁴Department of Physics, Hubei University, Wuhan, China

Quite after the discovery of high-temperature superconductivity in the cuprate compounds, it has been proposed that the essential physics of these materials is captured by the Hubbard model. Although this model is conceputally very simple, an exact solution is not known for more than one spatial dimension. Thus, approximate or numerical evaluations are needed for these quasi 2D materials. Our understanding of the ground-state properties of the 2D Hubbard model has improved a lot due to the development of the dynamical mean-field theory and its cluster extension. We will discuss recent results obtained by the variational cluster approach (VCA), focusing on the symmetry-broken phases at zero temperature. Besides the discussion of the competition between antiferromagnetism and d-wave superconductivity at low hole doping, we will focus on the doping evolution of the superconducting gap. We show that the Hubbard model is indeed able to describe the experimentally found two energy scales in the underdoped cuprates, and give a possible explanation of this feature in terms of a spin-fluctuation-mediated pairing mechanism.