Curie-Weiss susceptibility

Atomic-like f electron states in condensed matter were first studied in rare-earth and actinide metallic or non metallic compounds. There the multiplicity of the f states and related properties like magnetic moment, Curie-Weiss susceptibilities and spectra (where the crystal field splitting is measured) indicate that for most of the rare-earth series (RE) it is a good approximation indeed to consider those f electrons as atomic-like states. Then for the calculation of properties we can treat the f electrons in those compounds within the same approximations as for the core electrons and assume that the interaction between f electrons in different sites is carried through the conduction or the valence electrons. 

Curie-Weiss susceptibility). At T 7 this moment either disappears (is quenched ) or is strongly reduced. The Kondo effect is due to the mixing of 4f and conduction electrons, the degeneracy of the f-electron ground state and the strong Coulomb repulsion between electrons in a single f-shell. 

Recently spin fluctuations (Moriya and Kawabata, 1973a,b) which are characterized by electron correlations turned out to be important for describing the susceptibility, electrical-, thermal- and magneto-resistivities of itinerant ferro-magnets. Moriya (1976) pointed out that the thermodynamic properties of itinerant ferro- and antiferromagnets are mainly governed by the exchange enhanced spin fluctuation modes. At present the results of the spin fluctuation theory can account for the Curie-Weiss susceptibility without localized mo-... 

NpN. De Novion and Lorenzelli (1968) reported on ferromagnetism in NpN, detected by susceptibility measurements. In order to explain their inverse susceptibility curves, they had to rely on a modified Curie-Weiss law, which means they had to add a constant susceptibility, /g = 400 x 10 emu, to the Curie-Weiss susceptibility. However, measurements reported by Aldred et al. (1974) show a straight linear dependence of the inverse susceptibility on temperature, which means that for a clean sample the simple Curie-Weiss law holds. This should be a warning against overly detailed interpretations of results if the sample quality is not completely assured. 

Within the class of materials that display signatures characteristic for spin fluctuations, i.e. a Curie-Weiss susceptibility at high temperatures, which evolves with... 

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