Fermi Surface of Nickel from Galvanomagnetic Measurements

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Abstract
Measurements of the high‐field galvanomagnetic properties of nickel show that one electron‐sheet of its Fermi surface is multiply connected, and touches the {111} faces of the Brillouin zone as does the Fermi surface of copper. In magnetic fields up to 80 kOe applied in a nonsymmetry direction, the magnetoresistance saturates and the transverse voltage is linear, the Hall constant corresponding to one electron per atom within the experimental accuracy. The last result strongly suggests that nickel is uncompensated, and if so it is a direct consequence of the removal of the spin degeneracy of the d bands by the ferromagnetic exchange interaction. According to this explanation, one, and only one, sheet of the Fermi surface in a spin zone (i.e., a half‐band consisting of the states of a single sign of spin) of the 3d bands has an electronic character. The alternative explanation that the d bands contain only holes with a mobility at least two orders of magnitude smaller than the s‐band electrons, cannot yet be conclusively ruled out but seems most unlikely. This study of nickel has shown that the experimental methods used to investigate the Fermi surfaces of nonmagnetic metals may be taken over directly to determine the Fermi surfaces of the ferromagnetic metals.