3D versus 2D domain wall interaction in ideal and rough nanowires

The interaction between transverse magnetic domain walls (TDWs) in planar (2D) and cylindrical (3D) nanowires is examined using micromagneLic simulations. We show that in perfect and surface deformed wires the free TDWs behave differently, as the 3D TDWs combine into metastable stares with average lifetimes of 300 ns depending on roughness, while the 2D TDWs do not due to 2D shape anisotropy. When the 2D and 3D TDWs are pinned at artificial constrictions, they behave similarly as they interact mainly through the dipolar field. This magnetostatic interaction is well described by the point charge model with multipole expansion. In surface deformed wires with artificial constrictions, the interaction becomes more complex as the depinning held decreases and dynamical pinning can lead to local resonances. This can strongly influence the control of TDWs in DW-based devices. (C) 2015 Elsevier B.V. All rights reserved.