Magnetostriction of Single-Crystal Dysprosium, Gadolinium Iron Garnet, and Dysprosium Iron Garnet

The temperature and field dependences of the magnetostriction of dysprosium single crystals were measured from 78°K to room temperatures. In the paramagnetic region (T>178°K), the six lowest-order coefficients were measured and were found to vary as H2. At lower temperatures, due to the large uniaxial anisotropy, only the basal plane coefficient was measureable. The temperature and field dependences of this coefficient are adequately represented by the single-ion magnetoelastic coupling theory and are given as a function of the moment by λ=8.7×10−3I5/2[L−1(m)]. The temperature dependences of the magnetostriction coefficients of single-crystal GdIG and DyIG were measured from 78° to 400°K and found to be much larger and of opposite sign than that of YIG over most of the temperature range. This is due to the larger magnetoelastic coupling coefficient of the rareearth ions. Among the several interesting features are: the observance of magnetostriction compensation points, the sharp dip (and change of sign) of the apparent saturation magnetostriction at the magnetization compensation points, and the reversal in sign of the forced magnetostriction.