  We study spin-dependent electronic transport across
ferromagnet/superconductor ballistic junctions modeled using tight-binding
Hamiltonians with s, p and d orbitals and material-specific parameters. We show
that by accurately modeling the band structure of the bulk materials, one can
reproduce the measured differential conductance of Cu/Pb nanocontacts. In
contrast the differential conductance of Co/Pb contacts can only be reproduced
if an enhanced magnetic moment is present at the interface.
