Anisotropic properties of the layered superconductor Cu0.07TiSe2

The anisotropic superconducting properties of single crystals of Cu0.07TiSe2 were studied by measurements of magnetization and electrical resistivity. T-c is around 3.9 K, and the measured upper critical field (H-c2) values are similar to 1.25 and 0.8 T, for applied field parallel and perpendicular to the TiSe2 planes, respectively. The anisotropy ratio gamma(anis)=H-c2(ab)/H-c2(c) is close to 1.6 and nearly temperature independent. The lower critical field (H-c1) values are much smaller (similar to 32 Oe for H parallel to ab and 17 Oe for H parallel to c); demagnetizing corrections for field perpendicular to the thin plate crystals are required for the determination of H-c1(c). The anisotropy of the critical fields is described well by the anisotropic Ginzburg-Landau (GL) theory, and the characteristic GL parameters are determined and discussed.