Photoinduced dynamics of spinel MnV 2 O 4

By pump-probe optical reflectivity measurements, we studied the photoinduced dynamics of MnV2O4, which is a d2 Mott insulator and exhibits a simultaneous spin and orbital ordering accompanied by a structural phase transition at 57 K. We compared the present experimental results with the results of the steady-state optical measurement of the same compound and the steady-state and pump-probe optical measurements of Al-doped MnV2O4, in which the orbital ordering and structural phase transition are absent but the magnetic ordering exists. We found that the photoinduced dynamics of MnV2O4 can be separated into three components: (1) the suppression of the Mott-excitation peak, (2) the melting of the orbital ordering, and (3) the melting of the magnetic ordering. Furthermore, we found that the lattice distortion associated with the photoinduced structural phase transition from tetragonal to cubic induces a strain wave whose propagation velocity is discernibly smaller than that of a conventional shockwave.