Structural and magnetic properties of spinel FeV₂O₄ with two ions having orbital degrees of freedom

Spinel FeV₂O₄ with orbital degrees of freedom both at the Fe²⁺ and V³⁺ ions exhibits successive structural phase transitions. We studied this structural and magnetic properties as well as the correlation between the two. We found that the crystalline domains in the tetragonal or orthorhombic phases can be aligned by the applied magnetic field, inducing a large magnetostriction (∼1%). The competition and cooperation of Fe²⁺ and V³⁺ orbitals is the possible origin of these intriguing properties in FeV₂O₄.