Susceptibility formalism for magnetic and quadrupolar interactions in hexagonal and tetragonal rare-earth compounds

Abstract

A susceptibility formalism is developed for analyzing the magnetic and quadrupolar interactions in hexagonal and tetragonal rare-earth compounds. Symmetrized expressions are given for the one-ion magnetoelastic coupling and for the two-ion quadrupolar interactions. This formalism, derived from perturbation theory, leads to specific magnetic, strain, and quadrupolar susceptibilities considering both the crystalline-electric-field effects and quadrupolar interactions. It allows an analytical description of physical properties, such as the first- and third-order paramagnetic susceptibilities, the parastriction, and the elastic constants.