标题： 光激发碲中的动态磁旋不稳定性观测 显示英文标题

标题： Observation of a dynamic magneto-chiral instability in photoexcited tellurium

摘要： 在由非平衡状态驱动的带电手性费米子系统中，与磁场平行的电流可以通过使电磁波被放大而产生动态不稳定性。 类似不稳定性是否可以在手性固态系统中出现仍然是一个开放问题。 我们使用时域太赫兹（THz）发射光谱学，在元素碲中检测到了我们称之为“动态磁手性不稳定性”的特征，碲是一种结构上具有手性的晶体。 在适度外部磁场下进行瞬时光激发后，碲会发出由随时间放大的相干模式组成的太赫兹辐射。 我们提出了一种解释，该解释基于一个理论模型，该模型认为电磁波与碲中杂质受主态的红外活性振荡器相互作用，形成放大极化子，从而导致这种放大。 我们的工作不仅揭示了磁手性不稳定性的存在，还突显了其在手性材料中太赫兹波放大的潜力。 显示英文摘要

摘要： In a system of charged chiral fermions driven out of equilibrium, an electric current parallel to the magnetic field can generate a dynamic instability by which electromagnetic waves become amplified. Whether a similar instability can occur in chiral solid-state systems remains an open question. Using time-domain terahertz (THz) emission spectroscopy, we detect signatures of what we dub a ``dynamic magneto-chiral instability" in elemental tellurium, a structurally chiral crystal. Upon transient photoexcitation in a moderate external magnetic field, tellurium emits THz radiation consisting of coherent modes that amplify over time. An explanation for this amplification is proposed using a theoretical model based on a dynamic instability of electromagnetic waves interacting with infrared-active oscillators of impurity acceptor states in tellurium to form an amplifying polariton. Our work not only uncovers the presence of a magneto-chiral instability but also highlights its promise for THz-wave amplification in chiral materials.