  We present combined experimental and theoretical investigations on the
magnetic and magnetocaloric behavior of Nd$_2$NiMnO$_6$. The relative cooling
power (RCP) which quantifies the usefulness of a magnetocaloric (MC) material
is estimated to be $\approx 300$ J/Kg near the ferromagnetic transition at $T_C
\approx 195$ K. This RCP is comparable to the best known MC materials.
Additionally, the magnetic entropy change has a broad profile ($T_C - 50~{\rm
K} < T < T_C + 50~{\rm K}$) leading to an enhancement in the working-range of
temperatures for magnetocaloric based cooling. These features make
Nd$_2$NiMnO$_6$ a superior magnetocaloric material compared for example, to the
nonmagnetic counterpart Y$_2$NiMnO$_6$. We identify the mechanism for the
enhanced RCP which can guide search for future MC materials.
