Magnetic properties of interacting nanoparticles in a triangular lattice: Monte Carlo simulations
Magnetic properties of interacting nanoparticles in a triangular lattice: Monte Carlo simulations
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DOI：
10.1103/physrevb.77.104419
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发表时间：
2008-03-01
影响因子：
3.7
通讯作者：
Schwarzacher, W.
中科院分区：
文献类型：
--
作者：
Figueiredo, W.;Schwarzacher, W.
我们通过蒙特卡罗模拟研究了三角形晶格中相互作用的纳米粒子系统的磁性。小颗粒受到平面内磁场的作用，并通过远距离偶极相互作用耦合。它们还具有单轴各向异性能量，易于在三维空间中随机指向。我们假设单轴各向异性能量的强度为高斯分布。我们根据零场冷却曲线计算了系统的阻塞温度，作为偶极和平均单轴各向异性能量贡献之比的函数。阻挡温度随该比值线性增加，表明偶极相互作用的净效应是增加纳米粒子所见的有效能垒的高度。磁滞曲线也被确定为该比率的函数，我们表明，在偶极强度的小值下，矫顽力场表现出轻微的最小值。当偶极相互作用不可忽略时，我们观察到在矫顽力场附近垂直于磁场的磁化分量的急剧变化。
We study the magnetic properties of a system of interacting nanoparticles in a triangular lattice through Monte Carlo simulations. The small particles are subjected to an in-plane magnetic field and are coupled via long-range dipolar interactions. They also present uniaxial anisotropy energy, with the easy axes pointing randomly in three dimensions. We assume a Gaussian distribution for the strengths of the uniaxial anisotropy energy. We calculate the blocking temperature of the system from the zero-field-cooled curve as a function of the ratio between the dipolar and mean uniaxial anisotropy energy contributions. The blocking temperature increases linearly with this ratio, showing that the net effect of the dipolar interactions is to increase the height of the effective energy barriers seen by the nanoparticles. The hysteresis curves are also determined as a function of this ratio and we show that the coercive field exhibits a slight minimum for a small value of the dipolar strength. When the dipolar interactions are not negligible, we observe a steep variation in the component of the magnetization that is perpendicular to the magnetic field in the neighborhood of the coercive field.