近日，美国麻省理工学院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以及上海大学的曹世勋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太赫兹场驱动的磁振子上转换。相关研究成果已于2024年1月23日在国际知名学术期刊《自然—物理学》上发表。
该研究团队发现，强太赫兹场可以启动由中间磁共振介导的磁振子上转换过程。通过利用二维太赫兹偏振法，研究人员证实了倾斜反铁磁体中不同磁振子模式之间耦合的单向特性。此外，自旋动力学的计算进一步表明，这种耦合是具有倾斜磁矩的反铁磁体的普遍特征。这些研究结果揭示了一种诱导理想能量转移途径，以及在固体中实现相干磁振子之间太赫兹诱导耦合的方法。
据悉，光激励和非线性控制晶格振动已经成为一种强大的方法，使量子材料的性质偏离平衡态。将相干声子-声子相互作用推广到其他类型的集体模式之间的非线性耦合，将为设计固体的动态特性提供更多的可能性。例如，磁序-磁振子的集体激励可以在能量耗散极小的情况下传输信息。它们的相干和非线性控制为即将到来的自旋电子学和磁振子中，实现基于集体模式的信息处理和存储提供了有吸引力的途径。
附：英文原文
Title: Terahertz-field-driven magnon upconversion in an antiferromagnet
Author: Zhang, Zhuquan, Gao, Frank Y., Chien, Yu-Che, Liu, Zi-Jie, Curtis, Jonathan B., Sung, Eric R., Ma, Xiaoxuan, Ren, Wei, Cao, Shixun, Narang, Prineha, von Hoegen, Alexander, Baldini, Edoardo, Nelson, Keith A.
Issue&Volume: 2024-01-23
Abstract: Excitation and nonlinear control of lattice vibrations with light has become a powerful method to manipulate the properties of quantum materials out of equilibrium. Generalizing from coherent phonon–phonon interactions to nonlinear couplings among other types of collective mode would open additional opportunities to design the dynamic properties of solids. For example, the collective excitations of magnetic order—magnons—can carry information with little energy dissipation, and their coherent and nonlinear control would provide an attractive route to achieve collective-mode-based information processing and storage in forthcoming spintronics and magnonics. Here we discover that intense terahertz fields can initiate the processes of magnon upconversion mediated by an intermediate magnetic resonance. By utilizing two-dimensional terahertz polarimetry, we demonstrate the unidirectional nature of coupling between distinct magnon modes of a canted antiferromagnet. The calculations of spin dynamics further suggest that this coupling is a universal feature of antiferromagnets with canted magnetic moments. These results demonstrate a route to induce desirable energy transfer pathways and a terahertz-induced coupling between coherent magnons in solids.
DOI: 10.1038/s41567-023-02350-7
Source: https://www.nature.com/articles/s41567-023-02350-7