Magnetic analysis of rapidly quenched LaFe alloys-a ferromagnetically coupled ferromagnetic cluster system: II. Analysis of the magnetization of as-quenched alloys

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Abstract
For part I see ibid, vol.6, p.9393 (1994). The magnetization of rapidly quenched LaFe alloys with less than 12 at.% Fe, reported in part I, was analysed. The alloy can be considered as a random set of ferromagnetic clusters with inter-cluster ferromagnetic coupling. It was demonstrated that the magnetization of an alloy for different external fields and temperatures can be expressed as a function of either H/(T-TCinter) in the super-paramagnetic region (290Cinter is the asymptotic Curie temperature and w is the molecular-field constant for the inter-cluster coupling. The relations gave estimates of the average cluster size, 100-1500 Fe atoms, which depends not on the Fe concentration but on the quenching process. Magnetization in the ferromagnetic region, 5<T<250 K, was analysed by the use of the molecular-field approximation with distributed cluster size and exchange coupling constant.