Coherent quasiparticle evolution in charge transfer systems: A dynamical mean field theory

Using the two-band Hubbard Hamiltonian for transition metal-3d and oxygen-2p states with perovskite geometry, we investigate the evolution of coherent quasiparticles in charge transfer systems. It is shown that the recently observed change of the photoemission spectrum of CaxSr1-xVO3 upon Ca-doping can be understood as a consequence of the varying importance of charge transfer excitations compared to the excitations of the transition metal states. This demonstrates the dynamical character of the charge carriers near the metal-insulator instability and suggests that such systems are of charge transfer type rather than purely Mott-Hubbard. The calculations are based on a new approach of the dynamical mean field theory for transition metal compounds. The solution of the self-consistent dynamical mean field equations are performed using the non-crossing approximation.