Energy-efficient switching of nanoscale magnets requires application of a time-varying magnetic field characterized by microwave frequency. At finite temperatures, even weak thermal fluctuations induce perturbations in the magnetization that can accumulate in time, disrupt the phase locking between the magnetization and the applied field, and eventually compromise magnetization switching. It is demonstrated here that the magnetization reversal is mostly disturbed by unstable perturbations arising in a certain domain of the configuration space of a nanomagnet. The instabilities can be suppressed and the probability of magnetization switching enhanced by applying an additional stimulus such as a weak longitudinal magnetic field that ensures bounded dynamics of the perturbations. Application of the stabilizing longitudinal field to a uniaxial nanomagnet makes it possible to reach a desired probability of magnetization switching even at elevated temperatures. The principle of suppressing instabilities provides a general approach to enhancing thermal stability of magnetization dynamics.

中文翻译：

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增强纳米粒子最佳磁化反转的热稳定性

纳米级磁体的节能切换需要应用以微波频率为特征的时变磁场。在有限的温度下，即使是微弱的热波动也会引起磁化强度的扰动，这种扰动会随着时间的推移而累积，破坏磁化强度和施加磁场之间的锁相，并最终损害磁化强度切换。这里证明，磁化反转主要受到纳米磁体构型空间的某个域中出现的不稳定扰动的干扰。通过施加额外的刺激，例如确保扰动有界动力学的弱纵向磁场，可以抑制不稳定性并增强磁化翻转的概率。将稳定纵向场应用于单轴纳米磁体使得即使在高温下也能达到所需的磁化翻转概率。抑制不稳定性的原理提供了增强磁化动力学热稳定性的通用方法。