Spin dynamics in manganese oxides; Double-exchange interaction and orbital ordering

Kajimoto, Ryoichi  ; Yoshizawa, Hideki*

Manganese oxides with cubic perovskite structure, AMnO, are famous materials where the so-called colossal magnetoresistance effect arises upon hole doping on Mn sites. The materials are regarded as a typical system where coupling of degrees of freedom of spin, orbital, and charge induces a variety of physical properties. The fundamental properties of this system and the typical magnetic and orbital orderings are briefly described. Inelastic neutron scattering studies of the spin waves to clarify the influence of the double-exchange interaction and the orbital orderings on the magnetic interactions are reviewed.