Critical magnetic field of surface superconductivity in lead

The critical superconductivity field Hc3 is measured on lead single crystals. It is shown that the temperature dependence of Hc3/Hc in the vicinity of superconducting transition temperature Tc is essentially nonlinear. Relative changes in the value of Hc3/Hc 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.