Magnetic interactions in nanocrystalline SmFeCo

Several samples of enhanced-remanence nanocrystalline Sm15Fe19Co66 were prepared by mechanical alloying of the elementary powders followed by heat treatments. Sample A had a remanence ratio η=σr/σs=0.68 and Hc=7.1 kOe, while, for B, η=0.58 and Hc=10.4 kOe, and, for C, η=0.57 and Hc=12.6 kOe. The isothermal remanent magnetization Mr(H), obtained for different initial demagnetized states (ac, dc+, dc−), and the demagnetization remanence Md(−H), obtained for an initially saturated state, were determined. The ac-demagnetization Henkel plot showed both magnetizing and demagnetizing interactions as observed in other nanocrystalline magnets. A comparison with the moving Preisach model indicates the importance of both mean-field and random interactions.