The vortex-like excitations detected by Nernst signals in high-Tc superconductors

Abstract

The nature of the pseudogap state and its relation to the d-wave superconductivity in high-T_c superconductors is still an open issue. The vortex-like excitations detected by the Nernst effect measurements exist in a certain temperature range above superconducting transition temperature T_c, which strongly support that the pseudogap phase is characterized by finite pairing amplitude with strong phase fluctuations and imply that the phase transition at T_c is driven by the loss of long-range phase coherence. We first briefly introduce the electronic phase diagram and pseudogap state of high-T_c superconductors, and then review the results of Nernst effect for different high-T_c superconductors. Related theoretical models are also discussed.