Magnetic reorientation transition of Gd(0001)/W(110) films

The temperature-dependent magnetic properties of Gd(0001)/W(110) films were investigated using the magneto-optical Kerr effect. Measurements of hysteresis loops, remanent magnetization, and susceptibility were performed as a function of temperature and film thickness (d=10–130 nm). Well annealed films of sufficient thickness (d≥40 nm) show an anomalous temperature dependence of the coercive field ${\mathit{H}}_{\mathit{c}}$(T) and the remanent magnetization ${\mathit{M}}_{\mathit{r}}$(T). In addition, a second peak in the in-plane as well as out-of-plane susceptibility was observed for these films. All experimental results for thick films can consistently be explained by a reorientation transition between a low-temperature phase with uniform in-plane magnetization and a high-temperature phase with a nonvanishing out-of-plane magnetization component. The thickness dependence of the transition temperature ${\mathit{T}}_{\mathit{r}}$, as well as the absence of a remanent out-of-plane magnetization implies that the reorientation transition is associated with the formation of a domain structure.