Flux line lattice in high-Tc superconductors: anisotropy, elasticity, fluctuation, thermal depinning, AC penetration and susceptibility

Various properties of the flux-line lattice (FLL) in high-Tc superconductors are compiled, derived, and discussed. Useful general and updated expressions for the energy and magnetic field of arbitrary flux-line arrangements in anisotropic and layered superconductors are presented. From these follow the nonlocal elastic moduli of the FLL which are then applied to the intricate problems of thermal fluctuations and thermal depinning of the FLL and to the linear response of the FLL to applied AC fields. Explicit expressions are derived for the complex AC penetration depth, surface impedance, AC resistivity and for the AC susceptibility of films and cylinders, taking full account of elastic pinning and viscous drag of vortices, and of thermally activated linear flux creep or tunneling. These AC properties are then applied to vibrating superconductors and to thermally activated flux diffusion, which gives a quantitative explanation of the depinning lines observed in various experiments. Finally, the shear-limited critical current density is estimated and FLL decoration experiments are discussed. (orig.)