  An approach to adjusting the conduction band population for tuning the
magnetic and magnetocaloric response of EuO1-{\delta} thin films through
control of oxygen vacancies ({\delta} = 0, 0.025, and 0.09) is presented. The
films each showed a paramagnetic to ferromagnetic transition around 65 K, with
an additional magnetic ordering transition at higher temperatures in the oxygen
deficient samples. All transitions are observed to be of second order. A
maximum magnetic entropy change of 6.4 J/kg K over a field change of 2 T with a
refrigerant capacity of 223 J/kg was found in the sample with {\delta} = 0, and
in all cases the refrigerant capacities of the thin films under study were
found to exceed that reported for bulk EuO. Adjusting the oxygen content was
shown to produce table-like magnetocaloric effects, desirable for ideal
Ericsson-cycle magnetic refrigeration. These films are thus excellent
candidates for small-scale magnetic cooling technology in the liquid nitrogen
temperature range.
