Effect of antiferromagnetic grain size on exchange anisotropy in Ni-Fe/25 at% Ni-Mn films

摘要

The correlation between the antiferromagnetic (AF)grain volume, v_(AF) and the exchange anisotropy is discussedfor Ni-Fe/25 at% Ni-Mn system. In spite of various thicknesscombination of ferromagnetic (F) and AF layers, theunidirectional anisotropy constant, J_k commonly became largeand saturated with increasing v_(AF). The substantial coercivityoriginated from the AF layer decreased and became constant withincreasing v_(AF). These experimental results were wellexplained by a simple model based on Meiklejohn's single spinmodel. We concluded that increasing v_(AF) is key to induce theexchange anisotropy effectively in F/AF bilayers.