Hole dynamics in spin and orbital ordered vanadium perovskites

A theory of doped perovskite vanadates with spin and orbital orders is presented. Mobile holes are strongly renormalized by spin excitations (magnons) in the spin G-type and orbital C-type (SG-OC) order, and orbital excitations (orbitons) in the spin C-type and orbital G-type (SC-OG) one. Hole dynamics in a staggered t_2g orbital array is distinguished from that in the antiferromagnetic order and the e_g orbital one. The fragile character of the (SG-OC) order in Y_1-xCa_xVO₃ is attributed to the orbiton softening induced by a reduction of the spin order parameter.