Electronic structure and volume magnetostriction of rare-earth metals and compounds

A first-principle theory of spontaneous volume magnetostriction is presented. It is based on self-consistent electronic structure calculations for a magnetically ordered ground state and a disordered local moment state. The effect of highly localized 4f orbitals of rare-earth (R) atoms is taken into account by an open-core treatment within the local spin-density approximation. The theory is applied to hexagonal gadolinium and to selected intermetallic compounds with the cubic C15 Laves structure: RCo2 (R=Gd, Dy, Er) and GdAl2. The results are compared to those of experiment and discussed in terms of: (i) magnitudes of the local moments and (ii) volume-dependent exchange interactions.