Dynamical spin susceptibility of ferromagnetic nickel

Abstract

The frequency- and wave-number-dependent spin susceptibility of ferromagnetic nickel is investigated using a noninteracting-spin band model constructed with the help of detailed band-structure calculations of Callaway and Wang. The free-electron approximation is used for electrons in the $s$ band and the simple tight-binding wave function is used for electrons in the $d$ subbands. The calculations for the diagonal part of susceptibility function are carried out for the field wave vector $\stackrel{\ensuremath{\rightarrow}}{\mathrm{q}}$ along the three principal symmetry directions [100], [110], and [111], and the anisotropy is found to be quite small. Therefore the only results along [100] direction are reported in this paper. The contribution of minority spin ($\ensuremath{\downarrow}$) bands is found to be much larger than the contribution of majority spin ($\ensuremath{\uparrow}$) bands. The total diagonal part of the susceptibility function is compared with the results for the paramagnetic phase. It is found that the susceptibility function of nickel in the ferromagnetic phase is larger than that in the paramagnetic phase.