Anomalous enhancement of spin-orbital correlation effects induced by Mg doping in spinel MnV₂O₄

The magnetization and magnetostriction properties of Mn_1−xMg_xV₂O₄ (x = 0.00, 0.10, 0.15, 0.20) single crystals have been investigated under both static and pulsed magnetic fields, in which the magnetization and magnetostriction behaviors exhibit field-sweep-rate dependence, which are related to the spin-orbital-lattice coupling in these systems. Especially, anomalous enhancement of spin-orbital correlation was observed for x = 0.15. We attribute this enhancement to the tuning on the canting angle of V³⁺ ions by Mg²⁺-ions substitution. Furthermore, while the inter-vanadium distance R_V-V is important to determine the evolution of the properties in the doped cases proposed by many studies, our result suggests that R_V-V is not always dominant, the spin-orbital correlation effect can survive from the disordering induced by the variation of R_V-V and even be enhanced at proper doping level.