Temperature dependence of the magnetization in high fields in the diluted antiferromagnet Fe46%Zn54%F2

Magnetization measurements on the diluted antiferromagnet Fe46%Zn54%F2 were performed in fields up to H≂8 T. The difference between the Neel temperature TN = Tc (H=0) and the temperature where (δM/δT)H is maximum scales as H2/φ, with φ=1.46(2) and φ=1.50(2) for zero‐field‐cooled (ZFC) and field‐cooled (FC) procedures, respectively. The temperature where the ZFC and FC curves split from one another, Teq(H), yields a larger φ=1.56(4). The variation of the magnetization in the FC case, for T < Teq(H), is interpreted as being internal to the domains, while the larger value of (δM/δT)H in the ZFC case compared to the FC is attributed to the critical behavior in the random‐field Ising model (RFIM) regime around the transition temperature Tc(H).