  Epitaxial La1.85Sr0.15CuO4/La2/3Ca1/3MnO3 superlattices on (001)-oriented
LaSrAlO4 substrates have been grown with pulsed laser deposition technique.
Their structural, magnetic and superconducting properties have been determined
with in-situ reflection high energy electron diffraction, x-ray diffraction,
specular neutron reflectometry, scanning transmission electron microscopy,
electric transport, and magnetization measurements. We find that despite the
large mismatch between the in-plane lattice parameters of LSCO and LCMO these
superlattices can be grown epitaxially and with a high crystalline quality.
While the first LSCO layer remains clamped to the LSAO substrate, a sizeable
strain relaxation occurs already in the first LCMO layer. The following LSCO
and LCMO layers adopt a nearly balanced state in which the tensile and
compressive strain effects yield alternating in-plane lattice parameters with
an almost constant average value. No major defects are observed in the LSCO
layers, while a significant number of vertical antiphase boundaries are found
in the LCMO layers. The LSCO layers remain superconducting with a relatively
high superconducting onset temperature of about 36 K. The macroscopic
superconducting response is also evident in the magnetization data due to a
weak diamagnetic signal below 10 K for H || ab and a sizeable paramagnetic
shift for H || c that can be explained in terms of a vortex-pinning-induced
flux compression. The LCMO layers maintain a strongly ferromagnetic state with
a Curie temperature of about 190 K and a large low-temperature saturation
moment of about 3.5(1) muB. These results suggest that the LSCO/LCMO
superlattices can be used to study the interaction between the antagonistic
ferromagnetic and superconducting orders and, in combination with previous
studies on YBCO/LCMO superlattices, may allow one to identify the relevant
mechanisms.
