Das Modell der magnetischen Nahbereichs-Kopplung in seiner Erweiterung und Anwendung auf Gallium-Dotiertes α-Cr2O3 / The Extension of the Magnetic Cluster-Model and its Application to Gallium-doped α-Cr2O3

Abstract

The cluster model, developed for the ESR-absorption of a pure antiferromagnetic compound, has been modified to take into account the magnetic dilution. As bonding in a cluster is sensitive to its local geometry, the consideration is confined to the specific structure of α-Cr2O3. In this case, the incorporation of diamagnetic Ga3+ ions sets up eight local configurations with different coupling energies and distinct probabilities. It is assumed that the ESR-absorption of a doped crystal can be explained by the absorption within these configurations. The theory is able to predict the dependence on temperature and concentration for the ESR-intensity of gallium-doped Cr2O3 with an accuracy of about 3%. Numeral results of this fit are the magnetic coupling energies K1 = 183 cm-1 between nearest Cr3+ neighbours and K2 = 82.3 cm-1 between next-nearest Cr3+ neighbours