Vortex correlations in the liquid states ofBi2Sr2CaCu2O8+ywith tilted columnar defects

Abstract

The interlayer and intralayer vortex correlations are studied in ${\mathrm{Bi}}_{2}{\mathrm{Sr}}_{2}\mathrm{Ca}{\mathrm{Cu}}_{2}{\mathrm{O}}_{8+y}$ with tilted and nontilted columnar defects (CDs) by the Josephson plasma-resonance experiments under various field angles. The interlayer correlation is enhanced at the recoupling field, near which we observe clear triple-resonance peaks. The recoupling field is determined only by the density of CDs in the superconducting layer, irrespective of CD angles from the $c$ axis. In the low-field decoupled liquid state, we observe an increase of the interlayer correlations due to increased pinning by enlarged defects. By contrast, scaling analysis shows little effect of the pinning strength on the interlayer and intralayer correlations in the high-field recoupled liquid state.