Mesoscopic effect observed in YBa2Cu3O7-δ/La0.67Sr0.33MnO3 tunnel junctions

Transport properties of YBa2Cu3O7-δ/La0.67Sr0.33MnO3 tunnel junction are studied at low temperature. The conductance spectra showed pronounced size dependence, i.e., the sharp zero-bias peak transited to a peak-and-dip structure as the junction size becomes smaller (∼10 μm). The peak-and-dip structure is sensitive to applied magnetic field, and the dip position moves as the magnetic field increases. These results suggest that mesoscopic effects such as the phase coherent effect and Aharanov-Bohm effect coexist in the present junction, even though YBCO and LSMO have a strongly correlated electron system