标题： 磁序在铁磁外尔半金属中诱导出真正的手性声子 显示英文标题

标题： Magnetic order induced truly chiral phonons in a ferromagnetic Weyl semimetal

摘要： 手性声子是晶体中具有明确手性或螺旋性的振动模式，通常存在于缺乏倒置对称性的材料中。 在这里，我们报告在kagome铁磁外尔半金属Co3Sn2S2中发现了真正的手性声子模式，这是一种保持倒置对称性但破坏时间反演对称性的材料。 使用旋向分辨的磁拉曼光谱，我们在样品在居里温度以下零磁场冷却时，观察到平面内Eg双简并模式自发分裂成两个具有相反旋向的 distinct 手性声子模式，而无需施加外部磁场。 当我们扫描面外磁场时，这种Eg声子分裂表现出与材料磁化强度直接相关的明显滞后回路。 观察到的自发分裂在低温下可达1.27 cm-1，并随着温度升高而减弱，最终在居里温度时消失。 我们的发现突显了磁序在诱导手性声子中的作用，为通过磁化操控手性声子以及反之亦然提供了新方法。 此外，我们的工作为利用手性声子控制手性外尔费米子提供了新的可能性。 显示英文摘要

摘要： Chiral phonons are vibrational modes in a crystal that possess a well-defined handedness or chirality, typically found in materials that lack inversion symmetry. Here we report the discovery of truly chiral phonon modes in the kagome ferromagnetic Weyl semimetal Co3Sn2S2, a material that preserves inversion symmetry but breaks time-reversal symmetry. Using helicity-resolved magneto-Raman spectroscopy, we observe the spontaneous splitting of the doubly degenerate in-plane Eg modes into two distinct chiral phonon modes of opposite helicity when the sample is zero-field cooled below the Curie temperature, without the application of an external magnetic field. As we sweep the out-of-plane magnetic field, this Eg phonon splitting exhibits a well-defined hysteresis loop directly correlated with the material's magnetization. The observed spontaneous splitting reaches up to 1.27 cm-1 at low temperatures and diminishes with increasing temperature, ultimately vanishing at the Curie temperature. Our findings highlight the role of the magnetic order in inducing chiral phonons, paving the way for novel methods to manipulate chiral phonons through magnetization and vice versa. Additionally, our work introduces new possibilities for controlling chiral Weyl fermions using chiral phonons.