Characterization of Tl2Ba2CaCu2O8-Films and Single Crystals by an AC-Susceptibility Method
A specially designed ac-susceptometer is described, which allows one to determine the anisotropy of the magnetic response of small (0.08×0.5×0.6mm) HTSC-crystals or thin films. The technique is illustrated by two examples: 1. Determination of the penetration length λ(0) for Tl2Ba2CaCu2O8 films with the external field parallel to the film surface. 2. Anisotropic behavior of the magnetic losses, as given by the imaginary part χ″ (T), in Tl2Ba2CaCu2O8 single crystals with fields perpendicular and parallel to the c-axis. Additional results on a tilted crystal (20° tilt of the c-axis relative to the external field) are discussed in terms of a possible flux line entanglement transition.
KeywordsVortex Anisotropy Sapphire Thallium Grease
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