  We present a unique study of the frustrated spinel MgV2O4 which possesses
highly coupled spin, lattice and orbital degrees of freedom. Using large
single-crystal and powder samples, we find a distortion from spinel at room
temperature (space group F-43m) which allows for a greater trigonal distortion
of the VO6 octahedra and a low temperature space group (I-4m2) that maintains
the mirror plane symmetry. The magnetic structure that develops below 42 K
consists of antiferromagnetic chains with a strongly reduced moment while
inelastic neutron scattering reveals one-dimensional behavior and a single band
of excitations. The implications of these results are discussed in terms of
various orbital ordering scenarios. We conclude that although spin-orbit
coupling must be significant to maintain the mirror plane symmetry, the
trigonal distortion is large enough to mix the 3d levels leading to a wave
function of mixed real and complex orbitals.
