The generalised susceptibility and joint density of states of BCC europium

Abstract

It is well known that the rare-earth metal europium has helical spin ordering below the Neel temperature TN=91K. By using the tetrahedron method, the authors have calculated the generalised magnetic susceptibility chi (q) under the constant matrix element approximation from their self-consistent (SCF) band calculations, and they have made clear the relation between chi (q) and the nesting of the Fermi surfaces. The chi (q) curve they obtain has a maximum at mod q mod =0.36(2 pi /a). This shows very good agreement with the incommensurate period of the helix of Nereson's experimental results (1964). They have also calculated the interband joint density of states (JDOS). The JDOS curve shows that the first three maximum peaks occur at 1.54, 1.87 and 2.25 eV, which is in excellent agreement with the experimental results of Endriz and Spicer (1970).