THE STRUCTURE AND ELASTIC-MODULI OF FLUX LINE LATTICES IN ANISOTROPIS SUPERCONDUCTORS

The elastic moduli of flux line lattices in anisotropic superconductors are studied. In addition to the familiar compression, shear and tilt moduli the moduli which connect the strains in the lattice basal plane with the vortex tilt arise. These moduli vanish for magnetizing a superconductor in the anisotropy axis direction. The continuum of the flux line structures which appear in this case has the identical compression and shear moduli and various tilt moduli. In the "easy axis" anisotropy-type superconductor a hexagonal flux line lattice occurs for small inductions. When the field is directed in the ab plane of a crystal the lattice transforms to the rhombic symmetry one. By that, its elastic moduli and induction in the sample increase abruptly. In the "easy plane" type superconductors the vortex chain structures only are stable. The elastic moduli characterizing the stiffness of an isolated chain are large exponentially in comparison with the moduli describing the interchain coupling. For strongly anisotropic superconductors, the tilt moduli may change its sign with the H orientation close to the anisotropy axis c. In this case the flux line structure and its elastic moduli vary in the irreversible and jump-like way.