Magnetization‐vector measurements were made on a slowly rotating disk sample of Au85Fe15after cooling to 4.2 K from aboveTg(=52 K) in a 15‐kOe field that saturates the thermoremanence. ForMT, the magnetization component transverse to the applied fieldH, results are shown asHMTvs &thgr;, the sample‐rotation angle relative toH, for &thgr; cycled between 0° and 180° at each value ofH. ForH≲0.1 kOe,HMTvaries nearly reversibly in simple accord with an anisotropy fieldHK(0.41 kOe in size) that rotates rigidly with the sample. At higherH, the rotational hysteresis grows rapidly until, forH≳0.4 kOe, another simple but highly irreversible behavior is observed. From this behavior, it is deduced thatHKrotates relative to the sample isothermally when the torque on it exerted by the sample magnetization reaches the magnitude of a frictional torque. The frictional‐torque coefficient is seen to decrease steadily with increasingH, as confirmed by direct measurements of the rotations of the remanence that result from sample rotations in variousHat 4.2 K.