Control of pancake vortex distribution by in-plane fields in Bi2Sr2CaCu2O8+y

The moderately strong attractive interactions between pancake vortices and Josephson vortices in the crossing-lattices state of Bi2Sr2CaCu2O8+y are utilized to change the distribution of pancake vortices by Josephson vortices. We have confirmed such a controllability by demonstrating the changes in the number of pancake vortices by using a micro-Hall probe while changing only the in-plane field. Increase in the in-plane field results in an increase in the density of pancake vortices near the center of the sample, demonstrating the lensing effect of vortices. We have also succeeded in visualizing the lensing effect by the differential magneto-optical method. Effects of the history, the density of pancake vortices, and the temperature on the lensing effect are studied.