Anomalous Small-Angle Magnetic Scattering from Amorphous TbFe2and YFe2

Small-angle quasielastic neutron scattering measurements have revealed an intense magnetic component at low temperatures in amorphous Tb${\mathrm{Fe}}_2$ and Y${\mathrm{Fe}}_2$, in addition to a weak critical divergence at $T_c$ in Tb${\mathrm{Fe}}_2$. These observations are interpreted as evidence that spatial fluctuations remain "frozen in" below the Curie point of Tb${\mathrm{Fe}}_2$, and that only short-range order is achieved in Y${\mathrm{Fe}}_2$.