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 κ 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 ≊(B¯/${\mathit{B}}_{\mathit{c}1}$ ${)}^{1/2}$/(1-B¯/${\mathit{B}}_{\mathit{c}2}$ ${)}^{1/2}$ (B¯ is the flux density, $B_{c1}$ and $B_{c2}$ are the lower and upper critical fields). The melting temperature of the vortex lattice is reduced by the same factor.