Current- and Field-Driven Domain Wall Motion in L- and C-Shaped Permalloy Nanowires With Different Wire Widths

Abstract

We investigated the pulse-current-driven and magnetic-field-driven domain wall (DW) motion in permalloy nanowires with different shapes and wire widths. Two different nanowire types, 600 nm wide L- and 300 nm wide C- shaped, were considered by means of magnetic force microscope and anisotropic magnetoresistance measurement. We confirmed that every time head-to-head vortex DWs were placed at the specific places as we intended for both types of nanowires. We found similar critical current densities (~5 times 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sup> A/m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ) and DW velocity (~2.0 m/s) for both nanowires in spite of their different shapes and widths. Multiple vortex DWs were also observed when the applied current density exceeded only a few percent of the critical values. We also performed magnetic-field-driven DW propagations. From the pinning and depinning images and anisotropic magnetoresistance measurement, we found the magnetoresistance value of the single vortex type DW for the L-shaped permalloy nanowire.