Softening of the phonon spectrum below the magnetic-phase-transition temperature

Abstract
Mössbauer studies of Fe57 in DyFe2 and YFe2 at temperatures 0.5TcT1.1Tc were performed. Giant dips in the temperature dependence of the recoil-free fraction and the thermal shift were observed below Tc in DyFe2. In YFe2 a regular flat behavior was observed. These results are interpreted as evidence for the large influence of the spin fluctuations on the phonon spectrum through the huge magnon-phonon coupling present in DyFe2 and absent in YFe2.