Coherent acoustic phonons in a coupled hexagonal boron nitride-graphite heterostructure.

IF 2.3 2区物理与天体物理 Q3 CHEMISTRY, PHYSICAL Structural Dynamics-Us Pub Date : 2024-02-14 eCollection Date: 2024-01-01 DOI:10.1063/4.0000228

Arne Ungeheuer, Nora Bach, Mashood T Mir, Ahmed S Hassanien, Lukas Nöding, Thomas Baumert, Sascha Schäfer, Arne Senftleben

引用次数: 0

Abstract

Femtosecond optically excited coherent acoustic phonon modes (CAPs) are investigated in a free-standing van der Waals heterostructure composed of a 20-nm transparent hexagonal boron nitride (hBN) and a 42-nm opaque graphite layer. Employing ultrafast electron diffraction, which allows for the independent evaluation of strain dynamics in the constituent material layers, three different CAP modes are identified within the bilayer stack after the optical excitation of the graphite layer. An analytical model is used to discuss the creation of individual CAP modes. Furthermore, their excitation mechanisms in the heterostructure are inferred from the relative phases of these modes by comparison with a numerical linear-chain model. The results support an ultrafast heat transfer mechanism from graphite to the hBN lattice system, which is important to consider when using this material combination in devices.

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耦合六方氮化硼-石墨异质结构中的相干声子。

在由 20 纳米透明六方氮化硼（hBN）和 42 纳米不透明石墨层组成的独立范德华异质结构中研究了飞秒光激发相干声子模式（CAP）。利用超快电子衍射（可独立评估组成材料层中的应变动态），在对石墨层进行光激发后，在双层堆栈中确定了三种不同的 CAP 模式。分析模型用于讨论单个 CAP 模式的产生。此外，通过与数值线性链模型进行比较，从这些模式的相对相位推断出它们在异质结构中的激发机制。研究结果支持从石墨到 hBN 晶格系统的超快热传导机制，这对于在设备中使用这种材料组合非常重要。

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

Structural Dynamics-Us CHEMISTRY, PHYSICALPHYSICS, ATOMIC, MOLECU-PHYSICS, ATOMIC, MOLECULAR & CHEMICAL

CiteScore

5.50

自引率

3.60%

发文量

审稿时长

16 weeks

期刊介绍： Structural Dynamics focuses on the recent developments in experimental and theoretical methods and techniques that allow a visualization of the electronic and geometric structural changes in real time of chemical, biological, and condensed-matter systems. The community of scientists and engineers working on structural dynamics in such diverse systems often use similar instrumentation and methods. The journal welcomes articles dealing with fundamental problems of electronic and structural dynamics that are tackled by new methods, such as: Time-resolved X-ray and electron diffraction and scattering, Coherent diffractive imaging, Time-resolved X-ray spectroscopies (absorption, emission, resonant inelastic scattering, etc.), Time-resolved electron energy loss spectroscopy (EELS) and electron microscopy, Time-resolved photoelectron spectroscopies (UPS, XPS, ARPES, etc.), Multidimensional spectroscopies in the infrared, the visible and the ultraviolet, Nonlinear spectroscopies in the VUV, the soft and the hard X-ray domains, Theory and computational methods and algorithms for the analysis and description of structuraldynamics and their associated experimental signals. These new methods are enabled by new instrumentation, such as: X-ray free electron lasers, which provide flux, coherence, and time resolution, New sources of ultrashort electron pulses, New sources of ultrashort vacuum ultraviolet (VUV) to hard X-ray pulses, such as high-harmonic generation (HHG) sources or plasma-based sources, New sources of ultrashort infrared and terahertz (THz) radiation, New detectors for X-rays and electrons, New sample handling and delivery schemes, New computational capabilities.