Photo-induced optical anisotropy and coherent oscillations in a quasi-two-dimensional two-orbital model for LaMnO ₃

Ultrafast transient optical conductivity of spin-orbital ordered LaMnO ₃ was investigated theoretically. A quasi-two-dimensional Hubbard Hamiltonian based on a four-site Mn cluster was established to simulate the LaMnO₃ system. The time evolution of the transient optical conductivity was numerically calculated. Intensity oscillations of the optical conductivity were observed, which were interpreted as the result of the quantum interference between phonon-coupled orbiton excited states. Also, the photo-induced anisotropy was observed, which revealed the broken orbital symmetry of the optical excited state.