Momentum Dependence of Orbital Excitations in Mott-Insulating Titanates

C. Ulrich, L. J. P. Ament, G. Ghiringhelli, L. Braicovich, M. Moretti Sala, N. Pezzotta, T. Schmitt, G. Khaliullin, J. van den Brink, H. Roth, T. Lorenz, B. Keimer
2009 Physical Review Letters  
High-resolution resonant inelastic x-ray scattering has been used to determine the momentum dependence of orbital excitations in Mott-insulating LaTiO_3 and YTiO_3 over a wide range of the Brillouin zone. The data are compared to calculations in the framework of lattice-driven and superexchange-driven orbital ordering models. A superexchange model in which the experimentally observed modes are attributed to two-orbiton excitations yields the best description of the data.
doi:10.1103/physrevlett.103.107205 pmid:19792341 fatcat:krdsjvxzzjc3tegxhnnjsk3ifa