Dynamical Mean Field Study of Model Double-Exchange Superlattices

A theoretical study of [001] "double exchange" superlattices is presented. The superlattice is defined in terms of an $AB$O$_3$ perovskite crystal. Itinerant electrons hop among the B sites according to a nearest-neighbor tight binding model and are coupled to classical "core spins". The $A$ sites contain ionic charges arranged to form an [001] superlattice which forces a spatial variation of the mobile electron charge on the $B$ sites. The double-exchange interaction is treated by the dynamical mean field approximation, while the long range Coulomb interaction is taken into account by the Hartree approximation. We find the crucial parameter is the Coulomb screening length. Different types of phases are distinguished and the interfaces between them classified.