Thermal fluctuation and melting of the vortex lattice in oxide superconductors.

The thermal fluctuation of the vortex positions in type-II superconductors with large Ginzburg-Landau parameter {kappa} and weak pinning is drastically increased when calculated from the correct nonlocal elasticity of the vortex lattice. As compared to the usual (local) elastic result, the mean-square shear strain and vortex displacements increase by a factor of {approx}({ital {bar B}}/{ital B}{sub {ital c}1}){sup 1/2}/(1{minus}{ital {bar B}}/{ital B}{sub {ital c}2}){sup 1/2} ({ital {bar B}} is the flux density, {ital B}{sub {ital c}1} and {ital B}{sub {ital c}2} are the lower and upper critical fields). The melting temperature of the vortex lattice is reduced by the same factor.