Field- and temperature-dependent a.c. susceptibility of CeFe₂

Abstract

The a.c. susceptibility of a sample of CeFe₂, has been measured as a function of temperature (4.2–300 K) and static biasing field (0–1 kOe). These measurements confirm the occurrence of a paramagnetic-to-ferromagnetic transition near 240 K; while the value for the exponent δ = 3·0 ± 0·15 has been deduced, reliable estimates for other exponents γ and β are precluded by the presence of anisotropy (most probably spin-orbit coupling). The leading term a ₂, (T)H ² in the field dependence of the susceptibility has also been evaluated; its coefficient a₂(T) increases monotonically with increasing temperature between 4·2 K and the ferromagnetic ordering temperature. In particular, this coefficient displays no sharp anomaly at low temperatures where structure in the zero-field response is apparent.