Critical magnetic field of surface superconductivity in lead

The critical superconductivity field H _c3 is measured on lead single crystals. It is shown that the temperature dependence of H _c3/H _c in the vicinity of superconducting transition temperature T _c is essentially nonlinear. Relative changes in the value of H _c3/H _c reach approximately 30%, which cannot be described by the Ginzburg-Landau theory. The experimental temperature dependences lead to the conclusion that the surface superconducting transition temperature noticeably exceeds the superconducting transition temperature in the bulk of the semiconductor. The differences in the critical temperatures and in the Ginzburg-Landau parameters for lead are estimated.