A Material View on Extrinsic Magnetic Domain Wall Pinning in Cylindrical CoNi Nanowires

Abstract

Speed and reliability of magnetic domain wall (DW) motion are key parameters that must be controlled to realize the full potential of DW-based magnetic devices for logic and memory applications. A major hindrance to this is extrinsic DW pinning at specific sites related to shape and material defects, which may be present even if the sample synthesis is well controlled. Understanding the origin of DW pinning and reducing it are especially desirable in electrochemically deposited cylindrical magnetic nanowires (NWs), for which measurements of the fascinating physics predicted by theoretical computation have been inhibited by significant pinning. We experimentally investigate DW pinning in Co x Ni100–x NWs by applying quasi-static magnetic fields. Wire compositions were varied with x = 20, 30, and 40, while the microstructure was changed by annealing or by varying the pH of the electrolyte for deposition. We conclude that pinning due to grain boundaries is the dominant mechanism, decreasing inversely with both the spontaneous magnetization and grain size. Second-order effects include inhomogeneities in lattice strain and the residual magnetocrystalline anisotropy. Surface roughness, dislocations, and impurities are not expected to play a significant role in DW pinning in these wire samples.

Tuning Magnetic Properties of CoxNi100–x Nanodots: Micromagnetic Insights for Tailoring Enhanced Electrochemical Performance in Energy Storage Devices

“…The observed irregularities, such as asymmetries, broadening, and distortion in hysteresis loop shapes, could be attributed to magnetization fluctuations and localized spin disorder induced by edge defects. , Consequently, the pinning sites created by these edge defects impede the motion of domain walls during the magnetization reversal process, interacting with them and creating a restoring force that opposes their movement. This results in increased domain wall energy and a more gradual reversal, influencing the slope of the hysteresis loop . As a result, higher coercivity values are expected in different compositions of the real defective Co x Ni 100– x dots.…”

“…This results in increased domain wall energy and a more gradual reversal, influencing the slope of the hysteresis loop. 37 As a result, higher coercivity values are expected in different compositions of the real defective Co x Ni 100−x dots. This phenomenon is clearly depicted in our phase diagram (Figure 7), aligning well with both experimental and simulation reports.…”