  The interplay between covalency and magnetism is non-trivial and can be
harnessed for designing new functional magnetic materials. Based on a survey
using density functional calculations, we show that $TM\unicode{x2013}O$ bond
covalency can increase the total magnetic moment of spinel compounds of
$TMFe_2O_4$ composition ($TM = V-Ni, Nb-Pd$) which are isomorphic to the
much-researched magnetite. Accordingly, $PdFe_2O_4$ was found to exhibit the
highest magnetic moment of 7.809 ${\mu}_B$ per formula unit which is
approximately twice that of $Fe_3O_4$ with $T_c$ predicted to be well above
ambient. We further propose a practical method for synthesising $PdFe_2O_4$.
