de Haas-van Alphen Effect and Fermi Surface of Ferromagnetic Iron

An investigation of the de Haas-van Alphen effect in ferromagnetic iron is reported. Evidence has been found for several pieces of the minority-spin surface: the lens pockets along $\Delta$, a central electron surface at $\Gamma$, the electron balls along $\Delta$, and the hole octahedron at $H$. Several majority-spin pieces were also identified: the small and intermediate hole pockets at $H$, the large hole arm piece at $H$, and the large electron sheet at $\Gamma$. Evidence is also found for orbits that lie partly on the hole octahedron and partly on the hole arm surface. We attribute these orbits to two combined sheets, the hybrid octahedron and the hybrid hole arm piece. These two sheets have mixed spin character which implies that the bands which form these surfaces are spin-hybridized. The mixing of bands of opposite spin is believed to be caused by the spin-orbit interaction which resolves the accidental degeneracy produced at a band crossing. The Fermi surface obtained from this investigation is compared with several recent band-structure calculations.