Magnetic anisotropy of elongated thin ferromagnetic nano-islands for artificial spin ice arrays.
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.
Department of Physics, Kansas State University, Manhattan, KS 66506-2601, USA. wysin@phys.ksu.edu
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Wysin
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Moura-Melo
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Mól
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Pereira