Magnetic Order, Cluster Phenomena and Hyperfine Structure in Amorphous YFe2

Abstract
Mössbauer spectra of 57Fe measured inbulk‐sputtered YFe 2 ( a ‐ YFe 2 ) display temperature dependent behavior characteristic of long‐range magnetic order for T < T c = 55 ± 5 K . The spectral features are quite similar to those of other magnetically ordered amorphous rare‐earth‐Fe2 (R‐Fe2) alloys. Spectral resolution is maintained up to T ≃0.8 T c with no evidence for super‐ paramagnetic cluster phenomena. The average magnetic hyperfine field, H eff(T), closely follows an S =1 Weiss molecular field dependence with H ¯ eff (5 K ) = 233 kOe . This field is unexpectedly large and comparable with that measured in the heavy R‐Fe2 alloys. It does not follow the general trend of decreasing H eff(0) with decreasing rare‐earth moment. Our interpretation of the ordering scheme below Tc is similar to that in other R‐Fe2 alloys, which is not in agreement with earlier interpretations.