Magnetization properties and vortex phase diagram of Cu sub(x)TiSe sub(2) single crystals

We have investigated the magnetization properties and flux dynamics of superconducting Cu sub(x) TiSe sub(2) single crystals within a wide range of copper concentrations. We find that the superconducting anisotropy is low and independent on copper concentration ( gamma ~ 1.7), except in the case of strongly underdoped samples (x [< or =] 0.06) that show a gradual increase in anisotropy to gamma ~ 1.9. The vortex phase diagram in this material is characterized by a broad region of vortex liquid phase that is unusual for such a low-T sub(c) superconductor with low anisotropy. Below the irreversibility line the vortex solid state supports relatively low critical current densities as compared to the depairing current limit (J sub(c)/J sub(0) ~ 10 super(-7)). All this points out that local fluctuations in copper concentration have little effect on bulk pinning properties in this system.