Small angle elastic and inelastic neutron scattering in Fe 0.7Al 0.3

Abstract

Small angle elastic and high resolution inelastic neutron scattering measurements were performed on a single crystal of ordered Fe 0.7Al 0.3. The small angle scattering intensity drops rapidly above T c and a peak appears at lower temperatures whose position shifts with Q. Thermal hysteresis effects observed in the small angle scattering below 300 K suggests a slow relaxation motion of magnetic clusters in the ferromagnetic phase. Around 300 K, well-defined spin-wave scattering is observed which follows an E = DQ 2 dispersion relation with D = 17 meV Å 2. As the temperature is lowered, the spin-wave peaks fade into a quasielastic central component. An unusual property in the lower temperature region of the ferromagnetic phase was also found in the Q dependence of small angle scattering behavior.