Magnetic field influence on the proximity effect at YB a2 C u3 O7/ L a2/3 C a1/3Mn O3 superconductor/half-metal interfaces

Abstract

We experimentally study the superconducting proximity effect in high-temperature superconductor/half-metallic ferromagnet YBa2Cu3O7/La2/3Ca1/3MnO3 junctions, using conductance measurements. In particular, we investigate the magnetic-field dependence of the spectroscopic signatures that evidence the long-range penetration of superconducting correlations into the half-metal. Those signatures are insensitive to the applied field when this is below the ferromagnet's saturation fields, which demonstrates that they are uncorrelated with its macroscopic magnetization. However, the application of more intense fields progressively washes away the fingerprint of long-range proximity effects. This is consistent with the fact that the well-known magnetic inhomogeneities at the c-axis YBa2Cu3O7/La2/3Ca1/3MnO3 interface play a role in the proximity behavior.