Field-Induced "Exchange Flips" in a Randomly Diluted Antiferromagnet

High-field magnetization studies of the randomly diluted, anisotropic antiferromagnet ${\mathrm{Fe}}_x{\mathrm{Zn}}_{1-x}{\mathrm{F}}_2$ have confirmed the existence of novel single-spin "exchange flips," occurring at fields $H_0=\frac{1}{8}n{H}_E$ ($n=1,\dots ,5\mathrm{}$), as predicted by a classical spin computer simulation. Field direction hysteresis of $\frac{\mathrm{dM}}{d{H}_0}$ is shown to result from "crossover" behavior to states which have no long-range order.