SPIN-SPLIT MASSES AND METAMAGNETIC BEHAVIOR OF ALMOST-LOCALIZED FERMIONS

We discuss specific features of quasiparticles in a strong applied mag netic field and near the Mott-Hubbard localization: the strong spin de pendence of the de Haas-van Alphen oscillations, the maximum in the fi eld dependence of the linear specific-heat coefficient, and metamagnet ic behavior. These properties are obtained within the approach involvi ng auxiliary (slave boson) fields that provides both the Gutzwiller ba nd narrowing and a nonlinear molecular field. The simultaneous observa tion of all three properties provides a consistent set of predictions of the mean-field approach to the almost-localized Fermi liquid. The s ituation for heavy fermion system CeRu2Si2 is briefly discussed.