Zhang Zhuquan, Chien Yu-Che, Wong Man Tou, Gao Frank Y, Liu Zi-Jie, Ma Xiaoxuan, Cao Shixun, Baldini Edoardo, Nelson Keith A
Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
Department of Physics, The University of Texas at Austin, Austin, TX 78712, USA.
Sci Adv. 2025 May 23;11(21):eadv3757. doi: 10.1126/sciadv.adv3757. Epub 2025 May 21.
Parametric amplification, where one signal is enhanced by the action of another, offers both practical utility for boosting weak signals and fundamental insights into the nonlinear coupling between degrees of freedom. In condensed matter systems, interactions between collective modes offer avenues for nonlinear coherent manipulation of coupled excitations and quantum phases. Antiferromagnets, with inherently coupled magnon modes, provide a promising platform for nonlinear control of spin waves and magnetization. However, nonlinear magnon-magnon interactions have been only partially elaborated, leaving key gaps in the prospects for potential ultrahigh-bandwidth magnonic signal processing. Here, we excite two distinct coherent magnon modes in an antiferromagnet and find that the magnon mode with a lower frequency undergoes amplification when the higher-frequency mode is driven. We unveil the nonlinear excitation pathways of this stimulated parametric downconversion process by using polarization-selective two-dimensional terahertz spectroscopy. Our work provides fundamental insights into nonlinear magnonics in antiferromagnets, laying the groundwork for forthcoming spintronic and magnonic devices.
参量放大，即一个信号通过另一个信号的作用而增强，它既为增强微弱信号提供了实际用途，也为深入了解自由度之间的非线性耦合提供了基本见解。在凝聚态系统中，集体模式之间的相互作用为耦合激发和量子相的非线性相干操纵提供了途径。具有固有耦合磁振子模式的反铁磁体为自旋波和磁化的非线性控制提供了一个有前景的平台。然而，非线性磁振子 - 磁振子相互作用仅得到了部分阐述，在潜在的超高带宽磁振子信号处理前景方面留下了关键空白。在这里，我们在反铁磁体中激发两种不同的相干磁振子模式，发现当驱动高频模式时，低频磁振子模式会发生放大。我们通过使用偏振选择性二维太赫兹光谱揭示了这种受激参量下转换过程的非线性激发途径。我们的工作为反铁磁体中的非线性磁振子学提供了基本见解，为即将出现的自旋电子学和磁振子学器件奠定了基础。
