Dynamical Response And Competing Orders In Two-Band Hubbard Model

We present a dynamical mean-field study of two-particle dynamical response functions in a two-band Hubbard model across several phase transitions. We observe that the transition between the excitonic condensate and spin-state ordered state is continuous with a narrow strip of supersolid phase separating the two. Approaching transition from the excitonic condensate is announced by softening of the excitonic mode at the M point of the Brillouin zone. Inside the spin-state ordered phase there is a magnetically ordered state with 2 x 2 periodicity, which has no precursor in the normal phase.