  With x-ray absorption spectroscopy and polarized neutron reflectometry we
studied how the magnetic proximity effect at the interface between the cuprate
high-$T_C$ superconductor $\mathrm{YBa_2Cu_3O_7}$ (YBCO) and the ferromagnet
$\mathrm{La_{2/3}Ca_{1/3}MnO_3}$ (LCMO) is related to the electronic and
magnetic properties of the LCMO layers. In particular, we explored how the
magnitude of the ferromagnetic Cu moment on the YBCO side depends on the
strength of the antiferromagnetic (AF) exchange coupling with the Mn moment on
the LCMO side. We found that the Cu moment remains sizeable if the AF coupling
with the Mn moments is strongly reduced or even entirely suppressed. The
ferromagnetic order of the Cu moments thus seems to be intrinsic to the
interfacial CuO$_2$ planes and related to a weakly ferromagnetic intra-planar
exchange interaction. The latter is discussed in terms of the partial
occupation of the Cu $3d_{3z^2-r^2}$ orbitals, which occurs in the context of
the so-called orbital reconstruction of the interfacial Cu ions.
