Magneto-optical observations of crossing-lattice state in Bi2Sr2CaCu2O 8+y -: art. no. 212502

The evolution of vortex states and vortex-lattice melting processes in Bi2Sr2CaCu2O8+y under tilted fields are observed a by differential magnetooptical technique. The vortex-lattice melting transitions in the tilted vortex-lattice state and in the crossing-lattice state are found to be similar to each other. When the field is applied at large angles from the c axis, the nucleation position of the vortex-liquid paddle is shifted toward the direction of field inclination. The shift of the shielding current leading to the shift of the vortex dome naturally explains the observed phenomena. When a large in-plane field is applied, pancake vortices penetrate through one-dimensional channels starting from a fixed position at the sample edge. We can find a natural explanation for such a feature based on the crossing-lattice ground state.