Evidence of Polarons and Their Ultrafast Optical Undressing in a Topological Semimetal

IF 9.1 1区材料科学 Q1 CHEMISTRY, MULTIDISCIPLINARY

Nano Letters Pub Date : 2026-11-02 DOI:10.1021/acs.nanolett.6c04108

Lei Hou,Yunkun Yang,Heming Xia,Jun Yin,Pengcheng Ji,Yujun Zhang,Wen Xu,Faxian Xiu,Lan Ding

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Abstract

Polarons, formed by coupling electrons with lattice vibrations, are of intense interest in topological semimetals owing to their crucial role in dictating high-speed topological optoelectronics. However, polarons in topological semimetals have thus far been exclusively observed as light-induced transient quasiparticles, leaving equilibrium polarons and their ultrafast dynamics elusive. Here, using time-resolved magneto-terahertz spectroscopy, we demonstrate the ultrafast optical undressing of polarons in a Cd3As2 thin film. In equilibrium, a magnetic-field-induced spectral splitting near the 1.22-terahertz phonon mode reveals an 87% enhancement of the carrier effective mass due to the polaron effect. Upon photoexcitation, the enhanced carrier effective mass collapses within 5 ps, reflecting the transient undressing of this pre-existing polaronic state. Notably, this anomalous suppression contrasts sharply with prior studies where optical excitation exclusively triggers polaron formation in topological semimetals. This study provides deep insights into the ultrafast magneto-optical dynamics of pre-existing polarons, advancing the design of high-performance topological devices.

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拓扑半金属中极化子及其超快光学脱溶的证据

极化子是由电子与晶格振动耦合形成的，由于它们在高速拓扑光电子学中起着至关重要的作用，在拓扑半金属中引起了人们的强烈兴趣。然而，到目前为止，拓扑半金属中的极化子仅被观察为光诱导的瞬态准粒子，使得平衡极化子及其超快动力学难以捉摸。在这里，利用时间分辨磁太赫兹光谱，我们展示了Cd3As2薄膜中极化子的超快光学脱光。在平衡态下，磁场诱导的1.22太赫兹声子模式附近的光谱分裂显示，由于极化子效应，载流子有效质量提高了87%。在光激发下，增强的载流子有效质量在5ps内崩溃，反映了这种先前存在的极化态的瞬态解耦。值得注意的是，这种异常抑制与先前的研究形成鲜明对比，其中光激发完全触发拓扑半金属中的极化子形成。该研究为现有极化子的超快磁光动力学提供了深入的见解，推动了高性能拓扑器件的设计。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Nano Letters 工程技术-材料科学：综合

CiteScore

16.80

自引率

2.80%

发文量

1182

审稿时长

1.4 months

期刊介绍： Nano Letters serves as a dynamic platform for promptly disseminating original results in fundamental, applied, and emerging research across all facets of nanoscience and nanotechnology. A pivotal criterion for inclusion within Nano Letters is the convergence of at least two different areas or disciplines, ensuring a rich interdisciplinary scope. The journal is dedicated to fostering exploration in diverse areas, including: - Experimental and theoretical findings on physical, chemical, and biological phenomena at the nanoscale - Synthesis, characterization, and processing of organic, inorganic, polymer, and hybrid nanomaterials through physical, chemical, and biological methodologies - Modeling and simulation of synthetic, assembly, and interaction processes - Realization of integrated nanostructures and nano-engineered devices exhibiting advanced performance - Applications of nanoscale materials in living and environmental systems Nano Letters is committed to advancing and showcasing groundbreaking research that intersects various domains, fostering innovation and collaboration in the ever-evolving field of nanoscience and nanotechnology.