Shapiro steps in the fluxon motion in superconductors

Abstract
A method for studying the fluxon motion in superconductors is suggested based on so-called Shapiro steps in the current-voltage characteristics. These are similar to ones that appear in Josephson junctions. A knowledge of the properties of Shapiro steps would provide important information on the properties of fluxons. An exact, nonperturbative calculation of the sizes of Shapiro steps is given for a periodic field having the form of a symmetric pulse.