Han Mangui, Chen Wenbing, Deng Longjiang
State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 610054, China.
J Nanosci Nanotechnol. 2010 Nov;10(11):7079-82. doi: 10.1166/jnn.2010.2928.
In this paper, we have used the finite element micromagnetism theory to simulate the magnetization (M) reversal behaviors of cobalt nanotubes with different lengths (L = 400, 600, 800 and 1000 nm). The inner radius and outer radius of nanotubes are 50 nm and 100 nm respectively. The simulation results show that all the nanotubes exhibit significantly anisotropic behaviors: the easy magnetization axis is along the longitudinal direction. The coercivity values are found dependent on the dimensions of Co nanotubes. For the nanotube with a length of 400 nm, M reversal processes along the Z axis starts from the inner wall and propagates from the inside toward the outside. However, for other nanotubes, M reversal processes start from both ends of nanotubes. When the magnetic field (H) is applied along the hard axis, magnetic moments gradually change their directions into the opposite directions. The variations of the total Gibbs free energy have been calculated to support the observed differences in reversal processes.
在本文中，我们使用有限元微磁学理论来模拟不同长度（L = 400、600、800和1000 nm）的钴纳米管的磁化强度（M）反转行为。纳米管的内半径和外半径分别为50 nm和100 nm。模拟结果表明，所有纳米管均表现出明显的各向异性行为：易磁化轴沿纵向方向。发现矫顽力值取决于钴纳米管的尺寸。对于长度为400 nm的纳米管，沿Z轴的M反转过程从内壁开始，并从内部向外传播。然而，对于其他纳米管，M反转过程从纳米管的两端开始。当沿硬轴施加磁场（H）时，磁矩逐渐将其方向改变为相反方向。已计算出总吉布斯自由能的变化，以支持在反转过程中观察到的差异。
