Dresden 2006 – wissenschaftliches Programm

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MA: Magnetismus

MA 16: Micro- and Nanostructured Magnetic Materials II

MA 16.5: Vortrag

Dienstag, 28. März 2006, 12:45–13:00, HSZ 103

Calculation of the spontaneous magnetization of zinc ferrite unit cells with different distributions of cations at 0 K — •Morteza Mozaffari, Seid Ahmad Rastghalam, and Jamshid Amighian — Phys. Dept., The University of Isfahan, Hezarjarib st., Isfahan 81746-73441, IRAN.

In this work we have calculated spontaneous magnetization of ensembles of zinc ferrite unit cells having one-, ten- and a hundred-million members. For a unit cell of zinc ferrite, about 76.5 % of the cations are on the surface. On the other word broken bond density (BBD), which is the fraction of broken exchange bonds between surface spins with exchange bonds between surface and core spins unaffected, is nearly equal to 1. Bulk zinc ferrite has a normal spinel structure and as zinc ion has no magnetic moment, it has an antiferromagnet order with a Néel temperature of less than 10 K. Experimental studies have shown that nanometer size of zinc ferrite could have an inverse spinel structure with a non zero spontaneous magnetization. This is due to the canting and/or redistribution of spins on different sublattices. For each of the ensembles a pair of cations have been changed randomly for each member. For unit cells with a distribution according to a normal spinel structure we obtained a spontaneous magnetization (4πM,sub,0) of 1319.5 G. For others we obtained a range of spontaneous magnetizations from 188.49 to 4913.45 G. Spontaneous magnetization mean values for the all ensembles were obtained that is 1543.40 G.