Defect scattering in high T-c and colossal magnetoresistive tunnel junctions

Disorder causes both superconducting cuprate and colossal magnetoresistive manganite based tunnel junctions to depart from properties based solely on the superconductivity or magnetism inherent in the materials. Amorphous bar rier layers cause diffuse reflection of quasiparticle states at the insulat or-superconductor interface, resulting in a local quenching of the d-wave o rder parameter. A subdominant order parameter evolves at low temperatures i n these layers. In manganites, interface disorder reduces spin polarization and causes the tunneling magnetoresistance in spin valve devices to be sma ller than in junctions with less disorder. (C) 2000 Published by Elsevier S cience B.V.