交变磁体MnTe中光调制各向异性驱动的相干磁振子
Coherent Magnons Driven by Photomodulated Anisotropy in Altermagnetic MnTe
浏览论文内容
中文总结 AI 辅助
研究以碲化锰为平台，通过对奈尔矢量局部平衡取向等进行空间映射，给出自旋波能隙上限。利用弱六角形各向异性实现光调制驱动相干自旋波，高于阈值时呈现特定依赖关系，为交变磁自旋电子学提供新途径。
中文摘要 AI 辅助
碲化锰（MnTe）最近成为典型的g波交变磁体，为研究交变磁序的非平衡激发提供了理想平台。本文报道了同时对奈尔矢量的局部平衡取向φL(r)以及光激发自旋波的振幅Δφ(r,t)和频率Ω(r)进行空间映射。基于这些测量，我们对由固有各向异性引起的自旋波能隙给出了约60μeV（0.7K）的极低上限。这种异常弱的六角形各向异性（K6）使交变磁序极易受到光学调谐，能通过光致增强K6来驱动相干自旋波。高于阈值泵浦通量时，空间映射显示这种光调制表现为Δφ对φL的六重对称锯齿形依赖以及Ω的类摆线调制。最终，MnTe中奈尔矢量的近各向同性使得能够对电子能带结构中自旋分裂的取向进行光学和机械控制，为交变磁自旋电子学提供了新途径。
英文摘要
Manganese telluride ($\text{MnTe}$) has recently emerged as a prototypical $g$-wave altermagnet, providing an ideal platform to investigate the non-equilibrium excitations of altermagnetic order. Here, we report simultaneous spatial mapping of the local equilibrium orientation of the Néel vector, $φ_L(\mathbf{r})$, alongside the amplitude, $Δφ(\mathbf{r},t)$, and frequency, $Ω(\mathbf{r})$, of photoexcited spin waves. Based on these measurements, we place a remarkably low upper bound of $\approx 60~μ\text{eV}$ (0.7 K) on the spin-wave gap arising from intrinsic anisotropy. This exceptionally weak hexagonal anisotropy ($K_6$) renders the altermagnetic order highly susceptible to optical tuning, allowing coherent spin waves to be driven by a photoinduced enhancement of $K_6$. Above a threshold pump fluence, our spatial maps reveal that this photomodulation manifests as a six-fold symmetric sawtooth dependence of $Δφ$ on $φ_L$ and a cycloid-like modulation of $Ω$. Ultimately, the near-isotropy of the Néel vector in $\text{MnTe}$ enables optical and mechanical control over the orientation of spin-splitting in the electronic band structure, offering new pathways for altermagnetic spintronics.
