  The competition of superconductivity and magnetism in superlattices composed
of alternating YBa$_2$Cu$_3$O$_{7-d}$ and La$_{0.67}$Ca$_{0.33}$MnO$_{3}$ thin
films is investigated using low-energy optical spectroscopy. The thickness of
the superconducting YBCO layers is varied from 30 nm to 20 nm while the
thickness of the magnetic LCMO layers is kept constant at 20 nm. We clearly
observe that the superconducting condensate density in the superconducting
state of superlattice is drastically reduced by the magnetic subsystem which
may be connected with proximity effects that distort the gap symmetry and thus
suppress superconductivity.
