Investigation of the thermally activated wall movement in a wide range of temperature

If a thin ferromagnetic film is exposed to an external field which is lower than the coercivity for fast reversal, the walls may move slowly by the aid of thermal activation. This phenomenon is investigated in a wide temperature range (20 to 300°K for quantitative measurements, 3 to 300°K for qualitative observations). The results lead to a modification of the existing theory. Especially in the low-temperature range the wall motion caused by the internal fluctuation field is more effective than predicted by theory. At low temperatures the mobility of the walls under a constant field becomes surprisingly high. This leads to an enhanced sensitivity concerning creeping effects and should therefore be considered in the design of low-temperature computer devices. Explanations of this effect are discussed.