铁磁性外尔半金属中磁有序诱导的手性声子
Magnetic order induced chiral phonons in a ferromagnetic Weyl semimetal
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中文总结 AI 辅助
研究在具有反演对称性的铁磁性外尔半金属Co3Sn2S2中，利用螺旋度分辨磁拉曼光谱发现磁有序诱导Eg声子自发分裂为相反螺旋度的手性模式，分裂与磁化磁滞相关并在居里温度附近消失。
中文摘要 AI 辅助
手性声子是晶体中具有明确手性或旋向性的振动模式，通常存在于缺乏反演对称性的材料中。本文报道了在kagome（笼目）铁磁性外尔半金属Co3Sn2S2中发现手性声子模式，该材料保持反演对称性但破坏时间反演对称性。利用螺旋度分辨磁拉曼光谱，我们观察到在无外磁场条件下，当样品零场冷却至居里温度以下时，二重简并的面内Eg模式自发分裂为两个具有相反螺旋度的不同手性声子模式。当我们扫描面外磁场时，这种Eg声子分裂表现出明确的磁滞回线，并与材料的磁化强度直接相关。观察到的自发分裂在低温下可达1.27 cm-1，随温度升高逐渐减小，并在居里温度附近完全消失。我们的发现凸显了磁有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向操控开辟了新方法。此外，本工作还为利用手性声子控制手性外尔费米子引入了新的可能性。
英文摘要
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 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, in the absence 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, progressively diminishes with increasing temperature, and completely vanishes near 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.
