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説明:

Phonon dispersion in crystals determines many important material properties, but its measurement usually requires large-scale facilities and is limited to bulk samples. Here, we demonstrate the measurement of full phonon dispersion in nanoscale systems by using picosecond acoustics. A heterostructure sample was prepared consisting of layers of hexagonal boron nitride (hBN) sandwiching a thin layer of black phosphorous (BP), within which a strain pulse was generated by photoexcitation and observed with an optical probe in the BP layer. The strain pulse traversed to the few nanometer thick hBN layers, where it propagated to the edge and echoed back, like acoustic waves in Newton’s cradle. The echoes returning to the BP layer provided information on the frequency-dependent time-of-flight and group velocity dispersion of the sample system. Phonon frequency combs observed in the Fourier transform spectrum confirmed the strain wave round trips and demonstrated the feasibility of determining group velocity dispersion through photoacoustics.

権利情報:

• Creative Commons BY Attribution 4.0 International
  

キーワード: Phonon dispersion, picosecond acoustics, heterostructure

刊行年月日: 2024-06-13

出版者: Springer Science and Business Media LLC

掲載誌:

• npj 2D Materials and Applications (ISSN: 23977132) vol. 8 issue. 1 39

研究助成金:

• MEXT | Japan Society for the Promotion of Science 202115353
• MEXT | Japan Society for the Promotion of Science 23K04356

原稿種別: 出版者版 (Version of record)

MDR DOI:

公開URL: https://doi.org/10.1038/s41699-024-00475-8

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更新時刻: 2025-02-23 22:47:55 +0900

MDRでの公開時刻: 2025-02-23 22:47:56 +0900