AVS 45th International Symposium
    Magnetic Interfaces and Nanostructures Technical Group Friday Sessions
       Session MI-FrM

Paper MI-FrM6
Magnetic Reversal on Vicinal Surfaces

Friday, November 6, 1998, 10:00 am, Room 324/325

Session: Magnetization Dynamics and Magneto-Optics
Presenter: M.D. Stiles, National Institute of Standards and Technology
Authors: R.A. Hyman, Georgia Institute of Technology
M.D. Stiles, National Institute of Standards and Technology
A. Zangwill, Georgia Institute of Technology
Correspondent: Click to Email
Ultrathin films of magnetic material on non-magnetic vicinal substrates may be the simplest systems that exhibit non-uniform magnetization reversal. These systems can be modeled by equally spaced and infinitely long step edges separating flat terraces. The intrinsic four-fold anisotropy of the terraces is augmented by uniaxial anisotropy localized at the step edges. For in-plane magnetization, the zero temperature behavior of these systems depends on two dimensionless parameters: the ratio of the step anisotropy energy to the domain wall energy on the flat terraces, and the ratio of the terrace length to the domain wall width. Numerical results give a rich phase diagram for the hysteresis loop structure as a function of these two parameters. In some cases, simple analytic formula for the domain wall depinning field can be derived that agree well with numerical work. For some values of the system parameters, the calculated hysteresis curves exhibit the shifted loop structure found in experiments. The reversal processes are a combination of domain nucleation at step edges, depinning due to domain wall interactions, and coherent rotation in the center of flat terraces. No sharp transition separates the limit of reversal by coherent rotation from that of reversal by domain wall depinning from steps. Instead, there is a smooth crossover from coherent rotation dominated reversal to domain wall depinning dominated reversal and most major loop structures are obtained in both limits.