Depinning of domain walls in permalloy nanowires with asymmetric notches

Abstract

Effective control of the domain wall (DW) motion along the magnetic nanowires is of great importance for fundamental research and potential application in spintronic devices. In this work, a series of permalloy nanowires with an asymmetric notch in the middle were fabricated with only varying the width (d) of the right arm from 200 nm to 1000 nm. The detailed pinning and depinning processes of DWs in these nanowires have been studied by using focused magneto-optic Kerr effect (FMOKE) magnetometer, magnetic force microscopy (MFM) and micromagnetic simulation. The experimental results unambiguously exhibit the presence of a DW pinned at the notch in a typical sample with d equal to 500 nm. At a certain range of 200 nm < d < 500 nm, both the experimental and simulated results show that the DW can maintain or change its chirality randomly during passing through the notch, resulting in two DW depinning fields. Those two depinning fields have opposite d dependences, which may be originated from different potential well/barrier generated by the asymmetric notch with varying d.

Controlled spin-torque driven domain wall motion using staggered magnetic wires

“…To overcome these challenges, several ideas were proposed and tested; such as relying on natural defect [5052] and creating physically notches [53][54][55][56][57][58][59][60][61]. Other non-geometrical schemes such as modifying locally the magnetic properties of the ferromagnetic nanowire [6267] using exchange coupling [62,63], metal diffusion [64] or ionimplantation [65,66] were also investigated.…”

Staggered Magnetic Nanowire Devices for Effective Domain-Wall Pinning in Racetrack Memory

“…Artificial nanowires (NW) with naturally formed defects of different geometries acting as trapping sites have also been investigated using both numerical simulation and experimental observations [4,[31][32][33]. Several studies have also reported that experimentally creating notches using lithography helps to block or pin DWs [5,6,[34][35][36][37][38][39][40][41]. These artificial constrictions work as pinning sites for DWs due to their higher pinning potential than that of other pinning sites such as * rachid@squ.edu.om defects in the NWs.…”

Tilted magnetisation for domain wall pinning in racetrack memory

“…The critical challenge for DW memory application is the control of DW position at the nanoscale regime. In previous studies, many groups have reported that the creation of notches along the wire is a successful method for DW pinning by creating an energy potential [19][20][21].…”