Evidence for a Temperature-Dependent Surface Shielding Effect in Cu

Abstract

A large temperature-dependent transition in the magnitude of the ambient axial electric field inside a vertical copper tube has been observed. Above a temperature of 4.5 K the ambient field is 3 × ${10}^{-7\mathrm{}}$ V/m or greater. Below 4.5 K, the magnitude of the ambient field drops very rapidly, reaching about -5 × ${10}^{-11\mathrm{}}$ V/m at 4.2 K. We believe that these effects results from the presence of a surface electron layer on the inside wall of the tube which provides a temperature-dependent shielding effect.