GROUND STATE OF INTERLAYER JOSEPHSON VORTEX SYSTEMS BASED ON THE LAWRENCE–DONIACH MODEL

Ground state of interlayer Josephson vortex systems is investigated on the basis of the Lawrence-Doniach model. For low fields, the ground state is characterized by various rotated-lattice configurations, and inhomogeneity of the internal field and superconducting amplitude plays little role. For intermediate fields, the ground state is characterized by continuously-varying shearing angle of vortex lattices, and the shear instability field is enhanced by inhomogeneity of the internal field. For high fields, the upper critical field H_c2 is determined by inhomogeneity of the superconducting amplitude. For material parameters of cuprate high-T_c superconductors, the shear instability field is significantly increased, and H_c2 becomes infinite. These results are compared with the elastic theory and the London theory with respect to field dependence of the shear modulus c₆₆.