Influence of the nickel concentration on the magnetic properties of the cerium filled nickel substituted skutterudites

摘要

According to numerous authors, filled skutteruditeswhich are promising thermoelectric compounds are characterizedby very anomalous magnetic properties. Although containingcerium, iron and nickel or cobalt, these compounds, whatever thecomposition, do not order at low temperature. The magneticsusceptibility of nickel-poor compounds show a large deviationfrom the classical Curie-Weiss law. The effective magneticmoment of the semiconducting samples indicates that neithernickel nor iron are magnetic These properties could indicate atemperature depending valency of the cerium ion, a crystal fieldeffect or a heavy fermion behavior. In order to check some of thesehypotheses we have performed magnetic and X-ray absorptionexperiments on nickel substituted cerium filled skutterudites. Ourresults presented in this paper confirm the valency 3+ of thecerium ion and corroborate the heavy fermion hypothesis.