Vorticity, phase stiffness and the cuprate phase diagram

We review results obtained from vortex-Nernst experiments in cuprates. Evidence for a loss of phase coherence at the Meissner transition $T_{c0}$ is derived from vortex-like excitations that persist to high temperature. Below $T_{c0}$, the Nersnt signal provides a determination of the upper critical field $H_{c2}$ vs. doping $x$. Implications for the cuprate phase diagram are discussed.Comment: 6 pages, 8 figures, Plenary talk of the 7th International Conference on Materials and Mechanisms of Superconductivity and High Temperature Superconductors. To appear in Physica C, the proceeding of M2S-HTSC-VI