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 eta=sigma(r)/sigma(s)=0.68 and H-c=7.1 kOe, while, for B, eta=0.58 and H-c=10.4 kOe, and, for C, eta=0.57 and H-c=12.6 kOe. The isothermal remanent magnetization M(r)(H), obtained for different initial demagnetized states (ac, dc(+), dc(-)), and the demagnetization remanence M(d)(-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. (C) 1996 American Institute of Physics.