Direct observation of the vortex chain state in Bi 2Sr2CaCu2O8 + y by Bitter decoration

M. TOKUNAGA; T. TAMEGAI; YANINA FASANO; F. DE LA CRUZ

PHYSICAL REVIEW B - CONDENSED MATTER AND MATERIALS PHYSICS

Año: 2003 vol. 67 p. 134501 - 134504

0163-1829

We performed Bitter decoration on single crystals of Bi2Sr2CaCu2O8+y (BSCCO) in fields tilted from the c axis. By application of an out of plane field after zero-field cooling to about 30 K, we prepared vortex states with smooth density gradients throughout the sample. Bitter decoration of these states allowed us to detect the evolution to form the chain+lattice state as a function of magnetic induction along the c axis with single particle resolution in the same experiment. The observed vortex chains clarify the existence of an attractive interaction between pancake and Josephson vortices in both highly overdoped and optimally doped BSCCO. The results manifest the relevance of the crossing-lattices model in BSCCO beyond the theoretically predicted limit of the anisotropy parameter.