Abstract
Neutron inelastic scattering and diffraction techniques have been used to study the 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 orbitals. The anisotropy gap is a consequence of unquenched V orbital angular momentum.
- Received 13 November 2007
DOI:https://doi.org/10.1103/PhysRevLett.100.066404
©2008 American Physical Society