The effect of strong flux line correlations on the irreversibility line of high temperature superconductors

Abstract A phenomenological model is proposed to account for a recently observed crossover in the temperature dependence of the irreversibility line of high temperature superconductors from a (1 - T / T c ) 3 2 to a (1 - T / T c ) 3 dependence. The model, which distinguishes between weak correlations and strong correlations in the flux line lattice, indicates that the crossover should occur at magnetic fields corresponding to a flux line spacing of about λ/4, λ being the penetration depth transverse to the field.