Research Laboratory of Electronics, Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge, MA 02139, USA.
Beilstein J Nanotechnol. 2013;4:164-72. doi: 10.3762/bjnano.4.16. Epub 2013 Mar 4.
Self-assembled two-dimensional arrays of either 14 nm hcp-Co or 6 nm ε-Co particle components were treated by hydrogen plasma for various exposure times. A change of hysteretic sample behavior depending on the treatment duration is reported, which can be divided in two time scales: oxygen reduction increases the particle magnetization during the first 20 min, which is followed by an alteration of the magnetic response shape. The latter depends on the respective particle species. Based on the Landau-Lifshitz equations for a discrete set of magnetic moments, we propose a model that relates the change of the hysteresis loops to a dipole-driven ordering of the magnetocrystalline easy axes within the particle plane due to the high spatial aspect ratio of the system.
自行组装的二维阵列，其组成部分为 14nm 的 hcp-Co 或 6nm 的 ε-Co 颗粒，经氢等离子体处理不同的暴露时间。据报道，这种滞后样品行为的变化取决于处理时间的长短，可以分为两个时间尺度：在最初的 20 分钟内，氧还原增加了颗粒的磁化强度，随后改变了磁响应形状。后者取决于各个颗粒种类。基于朗道-利夫希茨方程对离散磁矩集，我们提出了一个模型，该模型将磁滞回线的变化与由于系统的高空间纵横比而导致的颗粒平面内磁晶易轴的偶极子驱动有序联系起来。
