Chapter 2 Magnetic properties of ternary intermetallic rare-earth compounds

Abstract

This chapter discusses the magnetic properties of ternary intermetallic rare-earth compounds. The values of the effective moments are deduced from the temperature dependence of the magnetic susceptibility. The disagreement between the experimental moments and the rare earth's free-ion moments is a result of a strong coupling of the conduction electrons with the localized moments. In the RKKY theory, the magnetic effective moment is given by the formula, described in the chapter. In the ternary rare-earth compounds discussed, the magnetic properties are determined by the rare-earth moments. The transition metal atoms T, except for Mn, do not carry magnetic moments. These materials have a metallic character and the interatomic distances between the rare-earth atoms are fairly large. The magnetic interaction between the highly localized 4f electrons is realized by their conduction electrons mediating in an exchange interaction, and by the effects of crystalline electric fields (CEF) acting on the 4f electrons. The chapter also reviews the influence of these factors on the magnetic properties. In metallic compounds of rare earths, exchange interactions between rare-earth moments are mediated by the spin polarization of conduction electrons. This leads to long-range exchange interactions with an oscillatory dependence of the interaction strength on the distance between the moments.