In-plane spin excitation of skyrmion bags

• Published in: Chinese physics B Vol. 32; no. 11; pp. 117503 - 664
• Main Authors: Li, Shuang, Li, Ke-Xin, Liu, Zhao-Hua, Zhu, Qi-Yuan, Zhao, Chen-Bo, Zhang, Hu, Shi, Xing-Qiang, Wang, Jiang-Long, Wang, Rui-Ning, Lian, Ru-Qian, Gong, Peng-Lai, Jin, Chen-Dong
• Format: Journal Article
• Language: English
• Published: Chinese Physical Society and IOP Publishing Ltd 01.10.2023
• Subjects: micromagnetic simulation; power spectral density; skyrmion bags; spin-wave mode; spin-wave mode; power spectral density; micromagnetic simulation; skyrmion bags
• ISSN: 1674-1056; 2058-3834; 2058-3834
• DOI: 10.1088/1674-1056/acd327

Skyrmion bags are spin structures with arbitrary topological charges, each of which is composed of a big skyrmion and several small skyrmions. In this work, by using an in-plane alternating current (AC) magnetic field, we investigate the spin-wave modes of skyrmion bags, which behave differently from the clockwise (CW) rotation mode and the counterclockwise (CCW) rotation mode of skyrmions because of their complex spin topological structures. The in-plane excitation power spectral density shows that each skyrmion bag possesses four resonance frequencies. By further studying the spin dynamics of a skyrmion bag at each resonance frequency, the four spin-wave modes, i.e., a CCW-CW mode, two CW-breathing modes with different resonance strengths, and an inner CCW mode, appear as a composition mode of outer skyrmion–inner skyrmions. Our results are helpful in understanding the in-plane spin excitation of skyrmion bags, which may contribute to the characterization and detection of skyrmion bags, as well as the applications in logic devices.