二维范德瓦耳斯反铁磁体系超快自旋动力学研究进展  

Recent Progress in Ultrafast Spin Dynamics in Two-Dimensional van der Waals Antiferromagnets

作　　者：李金阳 武方亮 张琦 LI Jin-yang;WU Fang-liang;ZHANG Qi(National Laboratory of Solid State Microstructures,Department of Physics,Nanjing University,Nanjing 210093,China)

机构地区：[1]南京大学物理学院,固体微结构物理国家重点实验室,南京210093

出　　处：《物理学进展》2024年第6期293-308,共16页Progress In Physics

基　　金：国家重点研发计划项目(No.2020YFA0309200)的资助。

摘　　要：反铁磁体具有太赫兹频段的高速自旋响应和对外磁场的鲁棒性,被视为下一代高速、高密度自旋信息器件的潜在材料。近年来,二维范德瓦耳斯磁性系统因其丰富的反铁磁基态和多样的物性调控手段而备受关注,成为探索低维反铁磁物理的理想平台。在这些二维反铁磁体系中实现超快自旋动力学的探测与调控对于推动高速自旋电子器件的应用至关重要。由于反铁磁体在宏观尺度上不表现出净磁矩,常规磁光探测技术难以直接观测其平衡态下的性质。然而,在非平衡状态下,通过时间分辨磁光克尔效应可以探测到由自旋动力学产生的瞬时磁化,从而揭示反铁磁自旋的相干运动。此外,线偏振二向色性光谱、太赫兹发射谱和二次谐波产生等技术也被广泛应用于二维反铁磁体系的动力学研究。本文综述了近期关于二维范德瓦耳斯反铁磁体系中超快自旋动力学的重要实验进展,并介绍了其中涉及的相干磁振子激发机制,包括逆磁光效应/受激拉曼散射、轨道共振激发以及激子耦合。此外,还探讨了自旋–晶格耦合导致的反铁磁自旋动力学的临界变慢现象,以及这种耦合对相干剪切声子模式的放大。Antiferromagnets exhibit high-speed spin responses in the terahertz frequency range and robustness against external magnetic fields, making them promising for nextgeneration high-speed, high-density spintronic devices. Recently, two-dimensional van der Waals magnetic systems, which possess rich antiferromagnetic ground states, have gained significant attention and serve as ideal platforms for studying low-dimensional antiferromagnetic physics. Detecting and controlling ultrafast spin dynamics in two-dimensional antiferromagnetic systems will lay the foundation for high-speed spintronic device applications. Antiferromagnets have no net macroscopic magnetization, making traditional optical methods, such as magneto-optical effects, challenging for detecting antiferromagnetic order in equilibrium states.However, in non-equilibrium states, the instantaneous magnetization generated by antiferromagnetic spin dynamics allows the use of time-resolved magneto-optical Kerr effect to detect coherent spin precession in antiferromagnets. Additionally, techniques such as linear dichroism spectroscopy, terahertz emission spectroscopy, and second harmonic generation have been employed in studying the dynamics of two-dimensional antiferromagnets. This paper introduces recent experimental progress on ultrafast spin dynamics in two-dimensional van der Waals antiferromagnetic systems, and briefly describes the coherent magnon excitations and corresponding mechanisms in two-dimensional antiferromagnets, including inverse magneto-optical effects/stimulated Raman scattering, orbital excitations, and exciton coupling. Furthermore,this paper discusses the critical slowing down of spin dynamics due to spin-lattice coupling effects and the amplification of coherent acoustic phonons.

关 键 词：反铁磁体 范德瓦耳斯材料 自旋动力学 磁振子 

分 类 号：O469[理学—凝聚态物理]