Magnetic excitations in amorphous Co4P

Neutron scattering techniques have been used to study the magnetic excitations in the amorphous ferromagnet Co4P. Distinct spin waves with a narrow line width have been measured near momentum transfer Q=O using a three axis spectrometer. The measurements around Q=O can ve performed only over a very restricted range in Q since the spin wave branch is quite steeply rising and at momentum transfers larger than 0.03 A−1 the spin wave energy is too high to conserve energy in the scattering process so that the scattering triangle cannot be closed. However, measurements were possible over a range of 0.005 to 0.03 A−1. These measurements could be well fit with quadratic dispersion law E=DQ2 if D has a value of about 185 meV A2. Polarized neutron time‐of‐flight measurements were able to show additional low‐lying spin wave excitations near the Q equal to the first peak in the static structure factor S(Q). The polarized beam technique is especially valuable for these measurements as only spin flip excitations are me...