Analyses of the Band Structure of Ferromagnetic Transition Metals from Neutron Scattering Data

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Recently photo electron emission and tunneling experiments succeeded in measuring the relative magnitudes of the up and down spin density of states of transition metals in the ferromagnetic state. These experiments indicate for Fe, Co and Ni that the density of states of the majority spin electron band is larger than that of the minority spin band at the Fermi surface. This observation is in contradiction with what has long been assumed on the simple parabolic band model for the 3d holes in these ferromagnetic transition metals. We present a new theoretical analysis of the magnetic elastic diffuse scattering of neutrons which give independent evidence that the majority spin bands can have the larger density of states in the ferromagnetic state of Fe. Recently we discussed the magnetic response of an electron gas in the ferromagnetic state to a charge or magnetic disturbance and emphasized the importance of the spin response due to a charge potential. We are able to relate the observed spatial behavior of the conduction electron spin polarization around an impurity to the band structure of the ferromagnetic host metals especially the relative magnitude of the density of states of the up and down spin electrons. We find that the parabolic band approximation for the 3d holes is in conflict with the neutron diffraction data and that the majority spin electron bands can have the higher density of states at the Fermi surface in the ferromagnetic state.