Vortex domain wall dynamics in stepped magnetic nanowire with in-plane magnetic anisotropy

Abstract

Controlling Vortex Domain wall (VDW) dynamics and stability in a stepped nanowire with in-plane magnetic anisotropy was investigated by using micromagnetic simulation with fixed nanowire dimensions. A stepped area is constricted at the center of the nanowire with proportions of length (d = 50 nm) and width (λ = 50 nm) to pin the magnetic domain wall (DW) with high barrier potential energy to achieve a high information storage capacity. From this study, it was found that the DW with different structures was pinned at the stepped area with high stability. Also, a reduction of VDW behaviors due to its chirality and polarity has been obtained according to saturation magnetization (Ms). By increasing the values of Ms, the VDW attraction to the nanowire edges based on its chirality and polarity becoming less and VDW moves in a straight line towards the stepped area. Therefore, with high values of MS, the VDW is stable in type and moves towards the stepped area with a speed of 500 m/s until pinning there. In addition, the symmetry of the stepped area design helps the VDW to move in a straight line through the stepped area and maintain its magnetization configuration during the depinning. This is important for writing and reading the information in storage memory devices.Furthermore, current density values (J) have affected the stability of the VDW by decreasing the VDW behaviors regarding its chirality and polarity. With low driven current density values, the VDW kept its structure until reaching and got pinning at the stepped area. Further investigations were done to examine the transverse domain wall (TDW) and VDW depinning through the stepped area. The results have shown that TDWs have a high barrier potential than VDWs.