ORIGIN OF LINEAR BACKGROUND MEASURED ON YBACUO-AU POINT-CONTACT JUNCTIONS

The differential conductance of YBaCuO-Au point contacts was measured after formation of contact by high bias voltage (up to +/- 2V). Change s of the differential conductance from a linear dependence to a quadra tic one and vice versa with respect to the bias voltage polarity aplie d were observed. These features were described in terms of inelastic t unneling due to strong electron-magnon interactions in the barrier. A good coincidence of theoretical and experimental characteristics indic ates that the linear background of differential conductance is not an intrinsic property of high-T-c superconductors