FERMI-SURFACE AND BAND-STRUCTURE OF FERROMAGNETIC COBALT

The principal sheets of the Fermi surface of cobalt measured by means of the de Haas-van Alphen effect are compared with the predictions of self-consistent ferromagnetic energy-band calculations both with and without spin-orbit contributions. The band calculations based on the local-spin-density approximation and using the linear-muffin-tin-orbital method provide a detailed interpretation of all the major sheets of the Fermi surface. The description of the smaller sheets of the Fermi surface from these calculations is not as good. However, a quantitative model for these sheets is presented which is consistent with only a minor change to the calculated band structure. As is often the case in strongly correlated electron systems, the agreement between the measured and calculated Fermi surface topologies is not reflected in the corresponding cyclotron masses. In particular, the measured cyclotron masses are found to be typically twice the predicted values and in agreement with the overall mass enhancement as obtained from the heat capacity.