Investigation of the current injection on JC of a HTS YBCO ring

The effect of the current injection from the ferromagnetic La0.7Sr0.3MnO3 (LSMO) electrode into high temperature superconducting Y1Ba2Cu3O7-x thin film ring on the critical current of the ring was investigated at 77 K using contactless method. The structures were prepared using magnetron sputtering, conventional photolithography and wet etching procedures. The critical current was determined from the response of the HTS ring to the AC magnetic field. The experiments demonstrated a sensitivity of the critical current to the current injection process, especially in the case of LSMO current-injecting electrode. The paper presents the experimental results and discusses possible mechanisms of the observed effects.