Dynamics of domain growth driven by dipolar interactions in a perpendicularly magnetized ultrathin film

Abstract

Measurements of the ac magnetic susceptibility of perpendicularly magnetized Fe/2ML Ni/W(110) ultrathin films show a clear signature of the dynamics of domain growth and domain density changes in the striped domain pattern that this system supports. The susceptibility peak measured at different constant heating rates in the range 0.20 K/s < R < 0.70 K/s shifts to higher temperature as the heating rate is increased. Analysis using a relaxation model demonstrates quantitatively that the dynamics is driven by a non-equilibrium domain density at (nearly) zero field (i.e. by dipole interactions), and that the temperature shift is due to a response time determined by the pinning of local domain wall segments by structural defects. The fundamental time scale for relaxation of the domain density driven by dipole interactions is of order 10^5 times slower than the fundamental time scale for an individual Barkhausen step driven by an applied field. The increase in the fundamental time scale reflects the relative size of dipole and Zeeman energies, and the need for the correlated motion of many local domain wall segments to affect domain growth.

11 pages, 5 figures

References in corpus (3)

• Creep and flow regimes of magnetic domain wall motion in ultrathin Pt/Co/Pt films with perpendicular anisotropy
• Interplay between coarsening and nucleation in an Ising model with dipolar interactions
• Dynamical signature of a domain phase transition in a perpendicularly-magnetized ultrathin film

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• Finite temperature phase diagram of ultrathin magnetic films without external fields
• Domain-wall free energy in Heisenberg ferromagnets
• Glassy behavior of two-dimensional stripe-forming systems
• Local and long-range realizations of a spin-reorientation surface phase transition
• Non-Arrhenius relaxation of the Heisenberg model with dipolar and anisotropic interactions
• Comparison of dynamical and equilibrium surface spin-reorientations: Inferences on the nature of the phase transitions in the presence of dipole interactions