High-field magnetization of (Cd,Mn)Te

The magnetization of the diluted antiferromagnetic system ${\mathrm{Cd}}_{1\mathrm{-}\mathrm{x}}$ ${\mathrm{Mn}}_{\mathrm{x}}$Te with 0.1≤x≤0.5 is examined up to fields of 40 T at liquid-helium temperature. The measured magnetization can be separated into the sum of two components: a paramagnetic Brillouin-type part that saturates by B=15 T, and a part linear in B. This separation only becomes evident at fields above 20 T. For increasing x, the ratio of the linear part to the saturating part increases. These characteristics appear to be universal for similar dilute systems, and are a consequence of the spin-spin coupling in small isolated clusters and the random network.