Field dependence of anisotropy in Ni, Dy, and Tb

Torque measurements have been made on single crystals of Ni, Dy, and Tb from 4.2 to 300 K using the high-field Bitter magnets of the University of Pennsylvania. For measurements up to 70 kOe, we used a 125-mm-bore radial access magnet fitted with iron pole pieces. For higher fields (up to 145 kOe), we used a 26-mm-bore axial access magnet, with the sample mounted on one of a pair of nylon bevel gears so the torque could be transmitted to an axial rod. In both cases, the torque was measured through a fixed lever arm and a pair of force transducers using unbonded resistance strain gages. The gages were excited at 4 kHz and the unbalance measured with a lock-in amplifier. Data on a