Energy loss and noise by chaotic motion of magnetic spin

磁自旋混沌运动造成的能量损失和噪声

基本信息

批准号：
10650269
负责人：
OKUNO Hikaru
金额：
$ 1.6万
依托单位：
Univ. of Tsukuba
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 2000
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10650269/
关键词：
magnetic material magnetic domain-wall magnetic domain chaos magnetic energy loss magnetic noise

项目摘要

The energy loss caused by the domain-wall motion is calculated by integrating damping term. The value of the energy loss is discussed in connection with the bifurcation diagram. The energy loss jumps to a high value at the first transition to chaos. The energy loss in the periodic window is larger than the value in the neighboring chaotic region in spite of their having the same damping coefficient.A chaotic region of domain wall motion is calculated as a function of the amplitude and frequency of the external magnetic drive field. It shows an intricate pattern composed of regular and chaotic regions. An energy loss and the Lyapunov exponent of domain wall motion are calculated. A frequency at the peak of the energy loss versus frequency curve, namely a nonlinear resonance frequency, is different from a resonance frequency in the linear theory as it shifts toward a lower frequency with increasing amplitude of the external magnetic drive field. This peak shift is explained by the effect … More of the higher order term in the nonlinear restoring force. The energy loss versus frequency curve becomes irregular and the energy loss decreases in the chaotic region where the Lyapunov exponent is positive.The two-step Ott-Grebogi-Yorke (OGY) method and the prediction OGY method for controlling chaos of magnetic domain-wall motion are proposed to improve the long settling time in the original OGY method. In the two-step OGY method, a magnetic domain wall is first moved on a periodic orbit and the OGY method is used when the orbit approaches a saddle point. In the prediction OGY method, the motion of the domain wall is predicted before the OGY method is applied. An attractor in the state space can be reconstructed by using the time series of the domain-wall motion. The near future can be predicted even in the chaotic system, because the short time developments of the neighborhood system of a predictee in the attractor are not so different from each other. The settling time of the improved OGY methods is 1/5-1/30 times as long as that of the original OGY method. Less

通过阻尼项造成的能量损失是与IFURCATION图的连接尽管具有相同的阻尼系数关闭主壁运动，但周期性窗口中的损失是邻居军团中的值，这是外部磁性驱动场的振幅和频率的函数。能量损失与频率曲线的峰值，即非线性谐振频率，与线性理论的要求不同，因为它向较低的率转移。能量损失与频率曲线IRREGLAR以及LYAPUNOV指数中的能量损失是正的。在两步的方法中，磁性域的原始方法首先在预测方法中移动。通过使用域壁的时间序列进行重建，即使在混乱的系统中也可以预测，因为只要您的吸引子的短时间开发，只要彼此之间的差异不大。原始方法