近日，美国麻省理工学院的Keith A. Nelson及其研究小组与美国德克萨斯大学奥斯汀分校的Edoardo Baldini等人合作并取得一项新进展。经过不懈努力，他们实现反铁磁体中两个磁振子模式的太赫兹场致非线性耦合。相关研究成果已于2024年1月31日在国际知名学术期刊《自然—物理学》上发表。

该研究团队展示了反铁磁体中不同磁振子模式之间的非谐波耦合的光谱指纹，通过两种模式的和频和差频的相干光子发射证明了这一点。这一发现是通过使用一对定制的太赫兹场来驱动两个相干磁振子模式，然后解开具有不同起源的非线性响应纠缠而实现的。这一研究的方法为产生非线性磁振子混合提供了一条新途径。

据悉，磁振子是磁有序材料中的量子化集体自旋波激发。揭示这些集体模式之间的相互作用对于理解这些系统中的基本多体效应，以及基于它们的高速信息传输和处理设备的发展至关重要。然而，确定单个磁振子模式之间的耦合仍然是一个长期的挑战。

附：英文原文

Title: Terahertz field-induced nonlinear coupling of two magnon modes in an antiferromagnet

Author: Zhang, Zhuquan, Gao, Frank Y., Curtis, Jonathan B., Liu, Zi-Jie, Chien, Yu-Che, von Hoegen, Alexander, Wong, Man Tou, Kurihara, Takayuki, Suemoto, Tohru, Narang, Prineha, Baldini, Edoardo, Nelson, Keith A.

Issue&Volume: 2024-01-31

Abstract: Magnons are quantized collective spin-wave excitations in magnetically ordered materials. Revealing the interactions among these collective modes is crucial for the understanding of fundamental many-body effects in such systems and the development of high-speed information transport and processing devices based on them. Nevertheless, identifying couplings between individual magnon modes remains a long-standing challenge. Here we demonstrate spectroscopic fingerprints of anharmonic coupling between distinct magnon modes in an antiferromagnet, as evidenced by coherent photon emission at the sum and difference frequencies of the two modes. This discovery is enabled by driving two magnon modes coherently with a pair of tailored terahertz fields and then disentangling a mixture of nonlinear responses with different origins. Our approach provides a route for generating nonlinear magnon–magnon mixing.

DOI: 10.1038/s41567-024-02386-3

Source: https://www.nature.com/articles/s41567-024-02386-3