Puzzling evidence for surface superconductivity in the layered dichalcogenide Cu10%10%TiSe2

•Combined specific heat and magnetotransport demonstrate surface superconductivity.•Surprisingly, surface effects occur for all magnetic field orientations.•Temperature dependence suggests a surface layer with depressed critical temperature.

We report on specific heat and magnetotransport measurements performed on superconducting Cu10%10%TiSe2 single crystals. We show that superconductivity persists in transport measurements up to magnetic fields HR well above the upper critical field Hc2 deduced from the calorimetric measurements. Surprisingly this “surface” superconductivity is present for all magnetic field orientations, either parallel or perpendicular to the layers. For H‖ab, the temperature dependence of the HR/Hc2 ratio can be well reproduced by solving the Ginzburg–Landau equations in presence of a surface layer with reduced superconducting properties. Unexpectedly this temperature dependence does not depend on the field orientation.