A theory of anomalies in the field dependence of the magnetization of strongly enhanced itinerant paramagnets

Misawa has shown, using phenomenological Landau theory, that in a normal Fermi liquid the leading correction to the linear dependence of magnetization M on applied magnetic field H is a term proportional to H 3 ln mod H mod . The authors give a fundamental derivation of this result and show that, subject to certain assumptions, the coefficient of this term varies as the sixth power of the exchange enhancement factor. It is pointed out that this term leads to features in the Arrott plot (M 2 against H/M) which provide a good fit to the observed low-field anomaly in stoichiometric Ni 3 Ga. The experimental data is fitted over a wider range of field by introducing a further term proportional to H 5 ln mod H mod . Other strongly enhanced itinerant paramagnets are discussed.