Experimental bulk electronic properties of ferromagnetic iron

Angle-resolved photoelectron spectroscopy utilizing synchrotron radiation has been used to determine the exchange splitting, band dispersion, band symmetries, and critical-point binding energies of ferromagnetic Fe. The magnetic ground-state electronic structure of Fe determined by recent ab initio calculations appears to be in good agreement with the results of our photoemission measurements. Correlation effects do not play a major role in influencing the $d$-band width and exchange splitting of Fe determined by photoemission (as appears to be the case for Ni); however, these effects are significant. Introduction of a Coulomb correction to calculated ground-state energies yields improved agreement with our photoemission results. Certain crystal faces and photon energies present experimental difficulties in studying bulk initial-state bands. In these instances, surface effects play an important role in the photoemission processes. These results show that the procedures and approximations, in particular the local exchange and correlation potentials, which have yielded accurate electronic structure models for nonmagnetic $d$-band metals, such as copper, are also able to yield accurate results for a ferromagnetic $d$-band metal.