  Based on the Hubbard model of strongly correlated systems, a reduction in the
bandwidth of the electrons can yield a substantial change in the properties of
the material. One method to modify the bandwidth is geometrically confined
doping, i.e. the introduction of a (thin) dopant layer in a material. In this
paper, the magnetic properties of LaVO$_3$/SrVO$_3$ superlattices, in which the
geometrically confined doping is produced by a one monolayer thick SrVO$_3$
film, are presented. In contrast to the solid solution La$_{1-x}$Sr$_x$VO$_3$,
such superlattices have a finite magnetization up to room temperature.
Furthermore, the total magnetization of the superlattice depends on the
thickness of the LaVO$_3$ layer, indicating an indirect coupling of the
magnetization that emerges at adjacent dopant layers. Our results show that
geometrically confined doping, like it can be achieved in superlattices,
reveals a way to induce otherwise unaccessible phases, possibly even with a
large temperature scale.
