Numerical investigation of domain walls in constrained geometries

作者：Fangohr Hans^*; Zimmermann Juergen P; Boardman Richard P; Gonzalez David C; de Groot Cornelis H

来源：Journal of Applied Physics, 2008, 103(7): 07D926.

DOI：10.1063/1.2838474

In recent years, magnetic domain wall structures in ferromagnetic nanowires have attracted growing attention, opening paths to develop novel devices which exploit magnetoresistive effects. A reduction of the domain wall length in geometrically constrained areas has been predicted and observed. In this article, we consider a rectangular constriction (width s(0), length 2d(0)) in form of a thin film, attached to a rectangular pad (width s(1)) on either side. The material considered is Ni (M(s)=490 kA/m) with a weak in-plane anisotropy (K(1)=2000 J/m(3)). We investigate the dependence of the domain wall length as a function of the constriction geometry. Micromagnetic simulations are used to systematically study the head-to-head domain walls between head-to-head domains (case A) and Neel walls between sidewise domain orientations (case B). We present the resulting domain wall length w as a function of 2d(0) and s(0) and analyze the magnetization patterns. A reduction of the domain wall length to below 11 nm is found (where the corresponding unconstrained domain wall length is 69 nm). For constriction lengths above a critical value (case B only), the single 180 degrees domain wall splits into two 90 degrees domain walls.

• 出版日期2008-4-1