Magnetic bistability and controllable reversal of asymmetric ferromagnetic nanorings.
Magnetic bistability and controllable reversal of asymmetric ferromagnetic nanorings.
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DOI：
10.1103/physrevlett.96.027205
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发表时间：
2005-08
影响因子：
8.6
通讯作者：
F. Zhu;G. Chern;O. Tchernyshyov;X. Zhu;J. Zhu;C. Chien
中科院分区：
文献类型：
--
作者：
F. Zhu;G. Chern;O. Tchernyshyov;X. Zhu;J. Zhu;C. Chien
对于半径约为50纳米的对称磁性纳米环，通过涡旋态的形成和洋葱态的旋转而产生的磁化反转是两个概率相当的过程。这种磁双稳现象是纳米磁体中交换能和静磁能竞争的表现。在对称纳米环中，这两个过程的相对概率由环的几何形状决定，在制造后不能改变。在这项工作中，我们报告了一种新型的纳米环--不对称纳米环。通过调节不对称性，我们可以利用外加磁场的方向将涡旋形成过程的比例从大约40%控制到近100%。观察到的结果与我们提供的理论计算中的局域截面积对磁畴壁能量的依赖关系有关。
Magnetization reversals through the formation of a vortex state and the rotation of an onion state are two processes with comparable probabilities for symmetric magnetic nanorings with a radius of about 50 nanometers. This magnetic bistability is the manifestation of the competition between the exchange energy and the magnetostatic energy in nanomagnets. The relative probability of the two processes in symmetric nanorings is dictated by the ring geometry and cannot be altered after fabrication. In this work, we report a novel type of nanorings--asymmetric nanorings. By tuning the asymmetry, we can control the fraction of the vortex formation process from about 40% to nearly 100% by utilizing the direction of the external magnetic field. The observed results have been accounted for by the dependence of the domain-wall energy on the local cross-section area for which we have provided theoretical calculations.