Magnetization reversal and soft modes in nanorings : Transitions between onion and vortex states studied by Brillouin light scattering
Magnetization reversal and soft modes in nanorings : Transitions between onion and vortex states studied by Brillouin light scattering
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DOI：
10.1103/physrevb.78.104421
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发表时间：
2008-09
影响因子：
3.7
通讯作者：
F. Montoncello;L. Giovannini;F. Nizzoli;H. Tanigawa;T. Ono;G. Gubbiotti;M. Madami;S. Tacchi;G. Carlotti
中科院分区：
文献类型：
--
作者：
F. Montoncello;L. Giovannini;F. Nizzoli;H. Tanigawa;T. Ono;G. Gubbiotti;M. Madami;S. Tacchi;G. Carlotti
我们提出了一个联合的实验和理论研究的磁化反转过程中的圆形坡莫合金纳米环阵列。磁光克尔效应测量的纵向磁滞回线表现出典型的两步开关行为，对应于从洋葱态到涡旋态的转变，反之亦然，在每个回线分支中都有平台。用动力学矩阵方法计算的这些组态的自旋激发频率与用布里渊光散射测量的结果吻合得很好。几种类型的自旋模式被发现定位在不同的区域的环。发现洋葱-涡旋和涡旋-洋葱的相变是由软自旋模式触发的。这些软模式的动态磁化曲线的形状和对称性提供了在转变开始时的磁化的初始修改。
We present a joint experimental and theoretical investigation of the magnetization reversal process in an array of circular permalloy nanorings. The longitudinal hysteresis loop measured by magneto-optic Kerr effect exhibits the typical two-step switching behavior corresponding to transition from the onion to the vortex state and vice versa with plateaux in each loop branch. The frequencies of the spin excitations in these configurations calculated by means of the dynamical matrix approach are in good agreement with those measured by Brillouin light scattering. Several types of spin modes are found localized in different regions of the rings. It is found that the onion-to-vortex and the vortex-to-onion transitions are triggered by soft spin modes. The shape and symmetry of the dynamic magnetization profile of these soft modes provide the initial modifications of the magnetization at the onset of the transitions.