Department of Physics, Faculty of Science, Cairo University, 12613 Giza, Egypt.
BLTP, JINR, Dubna, Moscow Region 141980, Russia.
J Phys Condens Matter. 2023 May 31;35(34). doi: 10.1088/1361-648X/acd73a.
We study the microwave-induced magnetization reversal in two systems, the microwave-driven nanomagnet (NM) and the NM coupled to a Josephson junction (JJ) under the microwave field (NM-JJ-MW). The frequency of the applied cosine chirp pulse changes nonlinearly with time to match the magnetization precession frequency. The coupling between the NM and JJ reduces the magnetization switching time as well as the optimal amplitude of the microwave field as a result of manipulating the magnetization via Josephson-to-magnetic energy ratio. The reversal effect in NM-JJ-MW is sufficiently robust against changes in pulse amplitude and duration. In this system, the increase ofdecreases the possibility of the non-reversing magnetic response as the Gilbert damping increases without further increase in the external microwave field. We also discuss the magnetic response of the NM driven by the ac field of two JJs in which the time-dependent frequency is controlled by the voltage across the junctions. Our results provide a controllable scheme of magnetization reversal that might help to realize fast memory devices.
我们研究了两个系统中的微波诱导磁化反转，一个是微波驱动的纳米磁体（NM），另一个是在微波场下与约瑟夫森结（JJ）耦合的 NM（NM-JJ-MW）。施加的余弦啁啾脉冲的频率随时间非线性变化，以匹配磁化进动频率。NM 和 JJ 之间的耦合通过约瑟夫森到磁能比来操纵磁化，从而减少了磁化翻转时间以及微波场的最佳幅度。NM-JJ-MW 中的反转效果对脉冲幅度和持续时间的变化具有足够的鲁棒性。在这个系统中，随着 Gilbert 阻尼的增加而增加，而外部微波场没有进一步增加，非反转磁响应的可能性减小。我们还讨论了由两个 JJ 的交流场驱动的 NM 的磁响应，其中时变频率由结上的电压控制。我们的结果提供了一种可控的磁化反转方案，可能有助于实现快速存储器件。
