The Nonlinear Behavior of Ferrites at High Microwave Signal Levels
The Nonlinear Behavior of Ferrites at High Microwave Signal Levels
复制标题
高微波信号水平下铁氧体的非线性行为
DOI：
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发表时间：
1956
期刊：
影响因子：
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通讯作者：
H. Suhl
中科院分区：
文献类型：
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作者：
H. Suhl
在一定的微波信号水平以上，铁氧体在其功率吸收中显示出各种异常。这些异常被观察到的条件下，某些“自旋波”在介质中的扰动增长到异常高的水平的条件相吻合。这种增长是由自旋波通过伴随扰动的退磁场和交换场耦合到均匀进动引起的。在第一部分的文件中，它示出的耦合导致某些自旋波振幅“跑掉”随时间的指数时，信号场超过阈值。这将最容易发生在谐振和适当的条件下，在一个范围内的直流偏置场限制在谐振的低端。在第二部分中，超过阈值信号的磁化的稳定状态被评估为一种类型的异常吸收。据发现，均匀的进动“饱和”在一个值对应的阈值信号，并进一步增加所施加的功率被转移到一个狭窄的范围内的自旋波。在新的状态下，计算可伸缩性。与实验的协议被发现是好的。由于该文件的目的是指导性质，分析保持在最低限度。完整的分析将在以后的出版物中发表。
Above a certain microwave signal level, ferrites show various kinds of anomalies in their power absorption. The conditions under which these anomalies are observed are shown to coincide with the conditions under which certain "spin wave" disturbances in the medium grow to abnormally high levels. This growth is caused by the coupling of the spin waves to the uniform precession through the demagnetizing and exchange fields that accompany the disturbances. In the first part of the paper it is shown that the coupling causes certain spin wave amplitudes to "run away" exponentially with time when the signal field exceeds a threshold value. This will happen most readily exactly at resonance and under suitable conditions in a range of dc biasing fields confined to the low side of resonance. In the second part, the steady state of the magnetization beyond the threshold signal is evaluated for one type of anomalous absorption. It is found that the uniform precession "saturates" at a value corresponding to the threshold signal, and that further increases in applied power are diverted into a narrow range of spin waves. The susceptibilities are computed in the new state. Agreement with experiment is found to be good throughout. Since the paper is intended to be tutorial in character, the analysis is kept to a minimum. The full analysis will be the subject of a later publication.