Magnetic-field dependence of tunneling conductance spectra of La0.67Sr0.33MnO3/YBa2Cu3O7-δ junctions in ultra-low temperatures

We precisely measured conductance spectra near the zero-bias conductance peak (ZBCP) in La0.67Sr0.33MnO3/YBa2Cu3O7-delta junctions, which reflects the formation of the surface bound states in the d-wave superconductors. When the conductance spectra of the junctions were measured at ultra-low temperatures (< 150 mK), very sharp ZBCPs were observed. We found the notable features of the magnetic field response of the ZBCP, i.e., the coexistence of spin-dependent and spin-independent components in the ZBCP and the apparent absence of the Zeeman splitting. (C) 2001 Elsevier Science B.V. All rights reserved.