Magnetization properties and vortex phase diagram of Cu <inf>x</inf>TiSe<inf>2</inf> single crystals

Abstract

We have investigated the magnetization properties and flux dynamics of superconducting CuxTiSe2 single crystals within a wide range of copper concentrations. We find that the superconducting anisotropy is low and independent on copper concentration (γ∼1.7), except in the case of strongly underdoped samples (x≤0.06) that show a gradual increase in anisotropy to γ∼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-Tc 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 c/J0∼10-7). All this points out that local fluctuations in copper concentration have little effect on bulk pinning properties in this system. © 2013 American Physical Society.