Chopin Chloé, de Wergifosse Simon, Moureaux Anatole, Abreu Araujo Flavio
Institute of Condensed Matter and Nanosciences, Université catholique de Louvain, Place Croix du Sud 1, 1348, Louvain-la-Neuve, Belgium.
Sci Rep. 2024 Oct 15;14(1):24177. doi: 10.1038/s41598-024-74094-0.
Micromagnetic simulations are used to study a spin-torque vortex oscillator excited by an out-of-plane dc current. The vortex core gyration amplitude is confined between two orbits due to periodical vortex core polarity reversals. The upper limit corresponds to the orbit where the vortex core reaches its critical velocity triggering the first polarity reversal which is immediately followed by a second one. After this double polarity reversal, the vortex core is on a smaller orbit that defines the lower limit of the vortex core gyration amplitude. This double reversal process is a periodic phenomenon and its frequency, as well as the upper and lower limit of the vortex core gyration, is controlled by the input current density while the vortex chirality determines the apparition of this confinement regime. In this non-linear regime, the vortex core never reaches a stable orbit and thus, it can be of interest for neuromorphic application as a leaky integrate-and-fire neuron for example.
微磁模拟用于研究由面外直流电流激发的自旋扭矩涡旋振荡器。由于涡旋核心极性的周期性反转，涡旋核心的回转幅度被限制在两个轨道之间。上限对应于涡旋核心达到触发第一次极性反转的临界速度的轨道，紧接着是第二次极性反转。在这次双极性反转之后，涡旋核心处于一个较小的轨道上，该轨道定义了涡旋核心回转幅度的下限。这种双反转过程是一种周期性现象，其频率以及涡旋核心回转的上限和下限由输入电流密度控制，而涡旋手性决定了这种限制机制的出现。在这种非线性状态下，涡旋核心从未达到稳定轨道，因此，例如作为一个泄漏积分发放神经元，它在神经形态应用中可能会受到关注。
