Reversible recovery of excess current in Y(Ho)–Ba–Cu–O–normal metal point contacts under high voltages
Abstract
A polarity-dependent reversible change in the current–voltage characteristics between states corresponding to different values of the excess current Iexc is observed for bias voltages of several hundred millivolts in Ag-ReBa2Cu3O7–x (Re = Y, Ho) point contacts in the current–carrying state. The observed effect has a high intensity (right up to a complete suppression or recovery of Iexc) and is not accompanied by a noticeable variation of the energy gap or the critical temperature in the point contact region. It is also established that the states with intermediate values of Iexc are stable for zero bias voltages across the point contacts, at least up to 110 K. It is assumed that the variation of Iexc and the coresponding modification of IVC are due to the oxygen migration processes induced by the electric field and current, resulting in a local variation of the superconducting parameters in the point-contact region.