Influence of end shape, temperature, and time on the switching of small magnetic elements

The switching characteristics of 10 nm thick permalloy elements with submicron widths has been studied by Lorentz microscopy. Of particular interest were the changes that occurred when the end-shape of the elements was modified. Gentle curving of the ends led to a reduction in switching field compared with an equivalent element with square ends. The principal reason for this was the different magnetization configurations found close to the element ends. At a temperature of 150 °C switching fields fell markedly, though those for elements with gently curved ends remained consistently lower. While most of the elements under study supported only high moment remanent states, intermediate low moment remanent states could be induced in elements of a certain size. The conditions under which this occurred are discussed.