Small-angle neutron scattering from amorphous ErFe2 and HoFe2 alloys

Small-angle neutron scattering measurements (SANS) have been made an amorphous ErFe2 and HoFe2 alloys as a function of temperature. These alloys show strong ‘‘subcritical’’ scattering as the temperature is lowered below their SANS-determined transition temperatures (Tf’s) of 105 K (±1 K) and 185 K (±5 K), respectively. The SANS line shapes are Lorentzian above Tf, but become increasingly non-Lorentzian below Tf and are consistent with a Lorentzian plus Lorentzian-squared cross section which is appropriate for these random anisotropy systems. The correlation lengths for ErFe2 and HoFe2 at low T are in the range of 60–70 Å. Near Tf ErFe2 shows a sharp peak, while for HoFe2 ξ is resolution limited over a range of 25 K below Tf.