Towards ab initio theory of 4f-magnetism at finite temperatures: Gd and Eu

The contribution reviews a simplified ab initio procedure to investigate basic properties of itinerant magnets containing 4f-electrons. The approach consists in two steps: (i) the selfconsistent electronic structure calculation within the density-functional theory with the 4f-orbitals treated as core orbitals, and (ii) the calculation of parameters of an effective classical Heisenberg Hamiltonian, which are determined using the magnetic force theorem and that are employed in subsequent evaluation of the magnon spectra, the spin-wave stiffness constants and the magnetic transition temperatures. Two elementary metals, namely the hcp Gd and the bcc Eu, are chosen to demonstrate the applicability of the developed scheme to various aspects of the itinerant 4f-magnetism: collinear and non-collinear magnetic ground states, long-ranged exchange interactions, and the resulting Curie/Neel temperatures. (author)