Effect of exchange-coupling interaction on domain pinning mechanism in nanometer permanent materials

The effect of exchange-coupling interaction on domain pinning mechanism in nanometer permanent materials has been investigated using random anisotropy model. Exchange-coupling coefficient alpha(ex) has been studied, and alpha(ex) corresponding to pinning fields is derived from coercivity formula, which is expressed as alpha(ex) = 3n/alpha pi(1+beta)(1/2)(1+beta-n)(1/2). Our results show that alpha(ex) is related with the degree of exchange-coupling interaction and properties of grain boundary. Coercivity decreases with the increasing degree of exchange-coupling interaction. Our results are accordant with other relative theoretical results. In order to obtain higher coercivity, exchange-coupling interaction between magnetically hard-hard grains should be weakened. (C) 2011 Elsevier B.V. All rights reserved.