Gareeva Zukhra, Guslienko Konstantin
Institute of Molecule and Crystal Physics, Subdivision of the Ufa Federal Research Centre of the Russian Academy of Sciences, 450075 Ufa, Russia.
Institute of Physics and Technology, Bashkir State University, ul. Z. Validi 32, 450076 Ufa, Russia.
Nanomaterials (Basel). 2023 Jan 23;13(3):461. doi: 10.3390/nano13030461.
A significant activity is devoted to the investigation of the ultrafast spin dynamic processes, holding a great potential for science and applications. However, a challenge of the understanding of the mechanisms of underlying spin dynamics in nanomaterials at pico- and femtosecond timescales remains under discussion. In this article, we explore the gyrotropic vortex dynamics in a circular soft magnetic nanodot, highlighting the impacts given by nutations in the high-frequency part of the dot spin excitation spectrum. Using a modified Thiele equation of the vortex core motion with a nutation term, we analyze the dynamic response of the vortex to an oscillating magnetic field applied in the dot plane. It is found that nutations affect the trajectory of the vortex core. Namely, we show that the directions of the vortex core motion in the low-frequency gyrotropic mode and the high-frequency nutation mode are opposite. The resonant frequencies of gyrotropic and nutational vortex core motions reveal themselves on different scales: gigahertz for the gyrotropic motion and terahertz for the nutations. We argue that the nutations induce a dynamic vortex mass, present estimates of the nutational mass, and conduct comparison with the mass appearing due to moving vortex interactions with spin waves and Doering domain wall mass.
一项重要活动致力于超快自旋动力学过程的研究，这在科学和应用方面具有巨大潜力。然而，在皮秒和飞秒时间尺度上理解纳米材料中潜在自旋动力学机制的挑战仍在讨论中。在本文中，我们探索圆形软磁纳米点中的旋向性涡旋动力学，突出了纳米点自旋激发谱高频部分的章动所产生的影响。使用带有章动项的涡旋核心运动的修正蒂勒方程，我们分析了涡旋对施加在纳米点平面内的振荡磁场的动态响应。发现章动会影响涡旋核心的轨迹。也就是说，我们表明在低频旋向性模式和高频章动模式下涡旋核心运动的方向是相反的。旋向性和章动性涡旋核心运动的共振频率在不同尺度上显现出来：旋向性运动为吉赫兹，章动为太赫兹。我们认为章动会诱导一个动态涡旋质量，给出章动质量的估计，并与由于移动涡旋与自旋波相互作用以及多林畴壁质量而出现的质量进行比较。
