Abstract
The magnetic and structural properties of single-crystal Fe1-xCoxV2O4 samples have been investigated by performing specific heat, susceptibility, neutron diffraction, and x-ray diffraction measurements. As the orbital-active Fe2+ ions with larger ionic size are gradually substituted by the orbital-inactive Co2+ ions with smaller ionic size, the system approaches the itinerant electron limit with decreasing V-V distance. Then, various factors such as the Jahn-Teller distortion and the spin-orbital coupling of the Fe2+ ions on the A sites and the orbital ordering and electronic itinerancy of the V3+ ions on the B sites compete with each other to produce a complex magnetic and structural phase diagram. This phase diagram is compared to those of Fe1-xMnxV2O4 and Mn1-xCoxV2O4 to emphasize several distinct features.
