In-plane vortex properties of Bi2Sr2CaCu2O8+delta single crystal and ESR anomalies

In order to investigate characteristic behaviors of the Josephson vortices, electron spin resonance (ESR) of free radical spins coated on the surface of the Bi2Sr2CaCu2O8+x crystal has been measured with the magnetic field pa rallel to the ab plane. The ESR linewidth is found to be narrow down to 55 K, below which the width broadens linearly. On the other hand, the integral intensity is observed to decrease at T-c. Possible origins for these ESR a nomalies are discussed, in relation to mobile nature of the Josephson vorte x lattice within the layer. (C) 2001 Elsevier Science B.V. All rights reser ved.