Determination of the antiferromagnetic exchange constant between nearest-neighborGd3+ions inPb0.95Gd0.05Te

For what is thought to be the first time high-field magnetization measurements are performed on a semimagnetic semiconductor with rare-earth-like magnetic ions (Gd). Saturation is reached at a field of 12.5 T. The experimental results are well fitted by the cluster model. The value of $J_{\mathrm{NN}}$ is determined: $J_{\mathrm{NN}\mathrm{\simeq }\mathrm{-}1.2}$ K.