  Here we present polarized neutron reflectometry measurements exploring thin
film heterostructures comprised of a strongly correlated Mott state, GdTiO$_3$,
embedded with SrTiO$_3$ quantum wells. Our results reveal that the net
ferromagnetism inherent to the Mott GdTiO$_3$ matrix propagates into the
nominally nonmagnetic SrTiO$_3$ quantum wells and tracks the magnetic order
parameter of the host Mott insulating matrix. Beyond a well thickness of 5 SrO
layers, the magnetic moment within the wells is dramatically suppressed,
suggesting that quenched well magnetism comprises the likely origin of quantum
critical magnetotransport in this thin film architecture. Our data demonstrate
that the interplay between proximate exchange fields and polarity induced
carrier densities can stabilize extended magnetic states within SrTiO$_3$
quantum wells.
