4f and Band Contribution to the Samarium Form Factor in Samarium Intermetallics

Abstract

During the last years, crystalline electric field (C.E.F.) and exchange interactions in rare earth ferro or ferrimagnetic alloys were successfully deduced from magnetic measurements on single crystals for numerous compounds (1–3). Indeed, the magnetization is closely related to exchange and crystalline fields. However, in HoZn (3) for instance, where exchange and C.E.F. are known from other experiments, the calculated magnetization curves along the three main crystallographic directions lie systematically below the experimental ones. This small discrepancy can be attributed to the polarization of conduction electrons which has been neglected. The failure of this approximation is emphasized in the case of samarium alloys where the spin and the orbital contributions to the total magnetic moment are opposite. In this case the band polarization, parallel to the spin, may be of the same order of magnitude as the total moment. The inaccuracy in estimating the band polarization on magnetization curves is then directly reflected in a large uncertainty on C.E.F. and exchange interactions.