  Neutron inelastic scattering and diffraction techniques have been used to
study the MnV2O4 spinel system. Our measurements show the existence of two
transitions to long-range ordered ferrimagnetic states; the first collinear and
the second noncollinear. The lower temperature transition, characterized by
development of antiferromagnetic components in the basal plane, is accompanied
by a tetragonal distortion and the appearance of a gap in the magnetic
excitation spectrum. The low-temperature noncollinear magnetic structure has
been definitively resolved. Taken together, the crystal and magnetic structures
indicate a staggered ordering of the V d orbitals. The anisotropy gap is a
consequence of unquenched V orbital angular momentum.
