Pulsed field differential magnetization, dM/dB, and Faraday rotation m
easurements are reviewed in selected dilute magnetic semiconductors wh
ich required fields above 30 T for determining the antiferromagnetic e
xchange interactions between isolated pairs of magnetic ions or large
clusters. In some cases, nonequilibrium effects result in a narrowing
(or broadening) of the peaks in dM/dB at the level crossing which prod
uce the magnetization steps at high fields. Similar measurements on a
molecular ferric wheel cluster of 10 Fe3+ ions are also discussed. Cri
tical field measurements in K3C60 and Rb3C60 and other superconductors
are briefly summarized. The pulsed field user facility is outlined.