铁磁中新激发态和形成机制  

New Excited States and Formation Mechanism in Ferromagnet

作　　者：李再东 田志欣 南雪萌 屈川 LI Zaidong;TIAN Zhixin;NAN Xuemeng;QU Chuan(School of Science,Tianjin University of Technology,Tianjin 300384,China;State Key Laboratory of Quantum Optics and Quantum Optics Devices,Shanxi University Taiyuan 030006,China;Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education,Lanzhou 730000,China)

机构地区：[1]天津理工大学理学院,天津300384 [2]山西大学量子光学与光量子器件国家重点实验室,山西太原030006 [3]兰州大学磁学与磁性材料教育部重点实验室,甘肃兰州730000

出　　处：《山西大学学报（自然科学版）》2022年第3期701-711,共11页Journal of Shanxi University(Natural Science Edition)

基　　金：量子光学与光量子器件国家重点实验室(山西大学)开放课题(KF202203);兰州大学中央高校基本业务费资助;兰州大学磁学与磁性材料教育部重点实验室开放课题资助(LZUMMM2021004);天津市研究生科研创新项目(2020YJSS169)。

摘　　要：文章介绍铁磁体中磁化强度运动的新激发态和形成机制,包括Akhmediev呼吸子、Kuznetsov-Ma孤子和怪波。在各向同性情况下,Landau-Lifshitz方程存在自旋波解和精确孤子解,在自旋波背景下激发磁孤子的过程,就形成了磁振子介导的自旋转移力矩。通过达布变换,给出了磁呼吸子的空间周期过程和自旋波背景的局域化过程,在极限情况下,首度得到磁化强度的精确怪波形式,并阐明其形成机制。为了明确上述激发态的相图,利用稳定性分析的方法得到自旋波的不稳定条件,发现不稳定区域就是磁振子介导的自旋转移力矩发生作用的区域,并且发现不稳定区域与Akhmediev呼吸子、Kuznetsov-Ma呼吸子和怪波之间的关系,并给出详细相图,验证了理论结果。In this paper,some new excited states and formation mechanism of magnetization motion are introduced analytically in ferromagnet,including Akhmediev breather,Kuznetsov-Ma soliton and rogue wave.In the isotropic case,the Landau-Lifshitz equation admits spin wave solutions and exact soliton solutions.The process of magnetic solitons in the spin wave background forms the magnon-mediated spin torques.In terms of Darboux transformation,the spatial periodic process of the magnetic breather and the localization process of the spin wave background are displayed in detail.In the limit case,the exact magnetic rogue wave solution is obtained for the first time,and its formation mechanism is also clarified.In order to clarify the phase diagram of the above excited states,the instability conditions of spin wave are obtained by using the stability analysis method.It is found that the unstable region is the effect region of the magnon-mediated spin torques.We also find the relationship between the unstable region and Akhmediev breather,Kuznetsov Ma breather and rogue wave.The detailed phase diagram is given to verify the theoretical results.

关 键 词：自旋波 磁孤子 呼吸子 怪波 调制不稳定性 磁振子介导自旋力矩 相图 

分 类 号：O441.2[理学—电磁学]