Band Structure, Spin Splitting, and Spin-Wave Effective Mass in Nickel

Abstract

We have applied a modified form of the combined interpolation (tight-binding plus pseudopotential) method to the calculation of energy bands in ferromagnetic nickel. A procedure has been developed to enable calculation of the reciprocal spin-wave effective mass in a multiband system in the $t$-matrix approximation. This has been used in conjunction with the calculated band structure. Matrix elements of the electron interaction are treated as parameters. A by-product of the calculation is an estimate, also in the $t$-matrix approximation, of the energy difference between majority and minority spin states in the highest $d$ band. Moderately good results for the spin-wave effective mass are obtained for reasonable values of the electron interaction parameters; however, a discrepancy is found in regard to the spin splitting, which appears to be too large.