Suppression of superconductivity in YBCO/LCMO superlattices

The competition of superconductivity and magnetism in superlattices composed of alternating YBa₂Cu₃O_7−d and La_0.67Ca_0.33MnO₃ thin films is investigated using low-energy optical spectroscopy. The thickness of the superconducting YBCO layers is varied from 30 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 super lattice is drastically reduced by the magnetic subsystem which may be connected with proximity effects that distort the gap symmetry and thus suppress superconductivity.