Investigation on the dynamics of cross-tie walls in elliptical permalloy elements

The magnetization reversal of micrometer-sized permalloy ellipses having cross-tie walls was investigated by means of magnetic-force microscopy and magnetoresistance measurements. Elliptical elements were fabricated using electron-beam lithography, in which an aspect ratio from 2 to 3 and thickness of 72 nm were accordingly designed. The magnetization reversal process illustrated main wall propagation along the short axis with the external field applied in the long-axis direction, while the reversal took place through annihilation of adjacent Nëel-type cores when the external field was applied in the short-axis direction. In addition, the longitudinal magnetoresistance curve showed many steps that are believed to be due to the propagation of the cross-tie wall associated with the annihilation of Nëel-type cores.