Theory of the diamagnetism above the critical temperature for cuprates

Abstract

Recently, experiments on high critical temperature superconductors have shown that the doping levels and the superconducting gap are usually not uniform properties but strongly dependent on their positions inside a given sample. Local superconducting regions may develop at the pseudogap temperature ${T}^{*}$ and upon cooling, grow continuously. As one of the consequences a large diamagnetic signal above the superconducting critical temperature ${T}_{c}$ has been measured by different groups. Here we construct a general theory to a disordered superconductor using a critical-state model for the magnetic response to the local superconducting domains between ${T}^{*}$ and ${T}_{c}$ and show that the resulting diamagnetic signal is in agreement with the experimental results.