Department of Physics, Kansas State University, Manhattan, KS 66506-2601, USA.
J Phys Condens Matter. 2012 Jul 25;24(29):296001. doi: 10.1088/0953-8984/24/29/296001. Epub 2012 Jun 22.
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.
本文研究了不同形状、纵横比和外加磁场方向的细长铁磁纳米岛的能量。这些纳米岛颗粒对于人工自旋冰材料很重要。在低温下，作为粒子净磁化方向的函数，通过数值方法计算单个粒子的磁内能。这导致了（1）易轴沿粒子长轴和（2）硬轴沿粒子薄轴的有效各向异性常数的估计。使用退磁场的自旋弛豫算法和快速傅里叶变换来解决薄系统的微磁问题。还发现了磁滞现象。结果表明，通过使用不同的岛几何形状，有可能控制自旋冰材料的平衡和动力学。
