1112.0913 (G. M. Wysin et al.)

Magnetic anisotropy of elongated thin ferromagnetic nano-islands for
artifical spin ice arrays    [PDF]

G. M. Wysin, W. A. Moura-Melo, L. A. S. Mól, A. R. Pereira

The energetics of thin elongated ferromagnetic nano-islands is considered for
some different shapes, aspect ratios, and applied magnetic field directions.
These nano-island particles are important for artificial spin-ice materials.
For low temperature, the magnetic internal energy of an individual particle is
evaluated numerically as a function of the direction of a particle's net
magnetization. This leads to estimations of effective anisotropy constants for
(1) the easy axis along the particle's long direction, and (2) the hard axis
along the particle's thin direction. A spin relaxation algorithm together with
fast Fourier transform for the demagnetization field is used to solve the
micromagnetics problem for a thin system. The magnetic hysteresis is also
found. The results indicate some possibilities for controlling the equilibrium
and dynamics in spin-ice materials by using different island geometries.

View original: http://arxiv.org/abs/1112.0913