MODELING OF MAGNETIC AND CRYSTAL DISORDER IN MAGNETIC OXIDES

Many crystalline materials have interesting properties, both scientifi cally and technologically, which are related to the detailed magnetic and crystalline structures on a local scale. Recent advances in e.g., GMR (Giant Magnetoresistance) materials, indicate an intimate coupling of the local spin structure to the conduction properties. However, al most all diffraction work on these and related materials concentrate o n the long-range crystal and magnetic structures. Only a few studies o f the local order have been performed and these have not simultaneousl y considered magnetic and atomic scattering. We have therefore develop ed a new reverse Monte Carlo (RMC) method for modeling both lattice an d magnetic disorder in powder crystalline materials by direct calculat ion of the structure factor. The method, and results from modeling tes t data on the lattice and magnetic structure of MnO around the Neel te mperature are presented. The prospects for modeling GMR materials are good. (C) 1998 Elsevier Science B.V. All rights reserved.