Surface resistance of type II superconductors: The surface barrier effect

The surface impedance of a type II superconductor plate occurring in the mixed state was calculated. In the case when a constant external magnetic field is perpendicular to the plate surface, the real part of the impedance (considered as a function of the magnetic field strength) exhibits a maximum, which is a manifestation of the dimensional effect. Behavior of the maximum was followed depending on the plate thickness and the alternating field frequency. On the passage to a planar geometry, an allowance for the Bean-Livingston barrier explains the formation of vortex-free regions near the plate surface, which leads to a decrease in the surface resistance and suppression of the size effect.