The superexchange interaction influence on the magnetic ordering in manganites

Manganese oxides such as La1−xSrxMnO3 and La1−xCaxMnO3 have been attracting considerable attention since the discovery of colossal magnetoresistance (CMR). These materials crystallize in the perovskite-type lattice structure where the crystal field breaks the symmetry of the atomic wave function of the manganese d electrons. The energetically lower t2g levels are occupied by three localized electrons. Due to a strong Hund coupling their spins are aligned, forming a localized corespin with S=3/2. The electron configuration of the Mn3+ ions is t2g3eg1, whereas for Mn4+ ions the eg electron is missing. Due to a hybridization of the eg wave function with the oxygen 2p orbitals, the eg electrons are itinerant and can move from a Mn3+ ion to a neighboring Mn4+ via a bridging O2−. In this paper, we present the ferromagnetic (FM) properties of the manganites obtained with the Monte Carlo working on a 2D system, using the ferromagnetic Kondo lattice model (FKLM), including the antiferromagnetic (AF) superexchange (SE) interaction. We investigate the spin–spin correlation function dependence with the electron density, the temperature dependence of structure factor, without the SE interactions and finally, the SE interaction influence of the FM ordering.