Spin Waves in 3<i>d</i> Metals

Abstract

A review is given of recent measurements of spin-wave dispersion relations of the 3d metals by the Brookhaven neutron diffraction group using the diffraction technique and triple-axis spectrometry. The parameters D and β in the relation ħω = Dq2(1 − βq2) have been determined at 295°K for Fe, Co, Ni, and some of their alloys. These values are compared with those obtained by thin-film resonance and small-angle scattering. The most extensive measurements were carried out on Fe using a triple-axis spectrometer. The dispersion relation was measured along the three principal symmetry directions for wavevectors up to q/qmax = 0.4. The stiffness constant D as well as the linewidth of selected spin waves were studied for the temperature range between 77°K and the Curie temperature, 1042°K. Well-defined magnons were observed up to a reduced temperature T/TC = 0.995, but not above TC.