Firstprinciples calculation of the magnetocrystalline anisotropy energy of iron, cobalt, and nickel
Abstract
The magnetocrystalline anisotropy energies of the elements iron, cobalt, and nickel have been calculated by means of the linear muffintin orbital (LMTO) method in the atomicsphere approximation (ASA) within the framework of the localspindensity approximation (LSDA). The socalled ``force theorem'' is used to express the totalenergy difference, when spinorbit coupling is included, as a difference in sums of KohnSham singleparticle eigenvalues. The results depend strongly on the location and dispersion of degenerate energy bands near the Fermi surface, and particular attention must be paid to the convergence of the Brillouinzone integral of the singleparticle eigenvalues. The calculated values of the anisotropy energy are too small by comparison with experiment, and we do not predict the correct easy axis for cobalt and nickel. We find that the variation of the anisotropy energy with changes in strain, in the magnitude of the spinorbit coupling, for different choices of the exchangecorrelation potential and for varying numbers of valence electrons are not capable of explaining these incorrect results. By comparing our calculated energy bands with those obtained by a fullpotential linear augmented plane wave (FLAPW) method we conclude that the discrepancy is not attributable to terms in the potential that are neglected in the ASA.
 Publication:

Physical Review B
 Pub Date:
 June 1990
 DOI:
 10.1103/PhysRevB.41.11919
 Bibcode:
 1990PhRvB..4111919D
 Keywords:

 75.10.Lp;
 75.30.Gw;
 71.25.Pi;
 Band and itinerant models;
 Magnetic anisotropy