Anisotropic phonon responses of 2D NbOX2 (X=Cl, Br, I) under uniaxial tensile strain

IF 3.6 2区物理与天体物理 Q2 PHYSICS, APPLIED

Applied Physics Letters Pub Date : 2025-02-10 DOI:10.1063/5.0253382

Xiaoyue Fan, Ziling Shen, Deng Hu, Youning Liu, Tianhong Tang, Wenchen Yang, Haiyang Liu, Yuxin Song, Qinsheng Wang, Baoli Liu, Zhiwei Wang, Jin-Jian Zhou, Gang Wang

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引用次数: 0

Abstract

The van der Waals crystal NbOX2 (X = Cl, Br, I) has recently attracted much attention due to its remarkable in-plane anisotropy and substantial second-order nonlinear optical response. Moreover, the importance of modulating its physical properties through strain has become increasingly prominent. Herein, we investigate the anisotropic phonon response of NbOX2 along various crystallographic directions under uniaxial tensile strain by Raman spectroscopy. The results show that opposing frequency shifts manifest in the Raman modes when uniaxial tensile strain is applied either parallel or perpendicular to the polar axis, and the highest frequency peak, P5, shows significant blue or red shifts. Density functional theory calculation results are consistent with the observed Raman shifts under strain. The change in Nb–O bond length is the main reason for the significant blue shift of P5. The anisotropic and pronounced frequency shifts of NbOX2 under strain can serve as sensitive indicators for strain modulation, offering insights for potential applications such as flexible optoelectronic devices and strain sensors.

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二维NbOX2 （X=Cl, Br， I）在单轴拉伸应变下的各向异性声子响应

范德瓦尔斯晶体 NbOX2（X = Cl、Br、I）因其显著的面内各向异性和大量的二阶非线性光学响应最近引起了广泛关注。此外，通过应变调节其物理性质的重要性也日益凸显。在此，我们通过拉曼光谱研究了 NbOX2 在单轴拉伸应变下沿不同晶体学方向的各向异性声子响应。结果表明，当施加平行或垂直于极轴的单轴拉伸应变时，拉曼模式会出现相反的频率偏移，最高频率峰 P5 会出现明显的蓝色或红色偏移。密度泛函理论计算结果与观察到的应变下的拉曼偏移一致。Nb-O 键长度的变化是 P5 发生明显蓝移的主要原因。NbOX2 在应变下的各向异性和明显频率偏移可作为应变调制的敏感指标，为柔性光电器件和应变传感器等潜在应用提供启示。

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

Applied Physics Letters 物理-物理：应用

CiteScore

6.40

自引率

10.00%

发文量

1821

审稿时长

1.6 months

期刊介绍： Applied Physics Letters (APL) features concise, up-to-date reports on significant new findings in applied physics. Emphasizing rapid dissemination of key data and new physical insights, APL offers prompt publication of new experimental and theoretical papers reporting applications of physics phenomena to all branches of science, engineering, and modern technology. In addition to regular articles, the journal also publishes invited Fast Track, Perspectives, and in-depth Editorials which report on cutting-edge areas in applied physics. APL Perspectives are forward-looking invited letters which highlight recent developments or discoveries. Emphasis is placed on very recent developments, potentially disruptive technologies, open questions and possible solutions. They also include a mini-roadmap detailing where the community should direct efforts in order for the phenomena to be viable for application and the challenges associated with meeting that performance threshold. Perspectives are characterized by personal viewpoints and opinions of recognized experts in the field. Fast Track articles are invited original research articles that report results that are particularly novel and important or provide a significant advancement in an emerging field. Because of the urgency and scientific importance of the work, the peer review process is accelerated. If, during the review process, it becomes apparent that the paper does not meet the Fast Track criterion, it is returned to a normal track.