Strongly driven superconductors: what the data tell us about Cuprates and organics

In the past decade, Cavalleri's group has reported "superconducting-like" behavior up to several times Tc in HiTc cuprates, the organic superconductors and K3C60. I will review some of the data and focus on the first two systems. In collaboration with M. Michael and E. Demler, I undertook a new analysis of the YBCO data. The goal is to find the minimal set of assumptions which can explain the observations. Unlike earlier discussions, we find that intense drive does not enhance the in-plane pair correlation or the inter-bilayer correlation. On the other hand, in order to explain the data, short range order within the plane and short range correlation between members of the same bi-layer are required in the equilibrium state. The implication is that pairing correlation survives up to the pseudogap scale. Therefore the pseudogap is a pairing gap. I will also discuss a suggestion with Zhehao Dai that the enhanced gap seen in the organics is an induced Mott gap rather than a pairing gap.