Neutron Scattering Study on the Spin-Orbital Coupling in Mn$_{\mathrm{1-x}}$Co$_{\mathrm{x}}$V$_{2}$O$_{4}$(x$=$0.2, 0.4, and 0.6)*

Two consecutive magnetic transitions have been reported in MnV$_{2}$O$_{4}$ compounds: the first transition is collinear and is from paramagnetic to ferrimagnetic state; The second transition, which is noncollinear, is accompanied by a tetragonal distortion, which produces an excitation gap in the magnetic spectrum [1]. However, the V-V distance is interfered with Co doping, and there is no structural phase transition observed in CoV$_{2}$O$_{4}$ down to 10 K [2]. In order to study the Co-doping effects on the structural and magnetic properties of Mn$_{\mathrm{1-x}}$Co$_{\mathrm{x}}$V$_{2}$O$_{4}$, elastic and inelastic neutron scattering is applied in our experiments and the interaction between magnetism and orbital will be discussed.\\[4pt] [1] V. O. Garlea, et al.,Phys. Rev. Lett. \textbf{100}, 066404 (2008);\\[0pt] [2] A. Kismarahardja, et al., Phys. Rev. Lett. \textbf{106}, 056602 (2011)