中国物理B ›› 2024, Vol. 33 ›› Issue (5): 56502-056502.doi: 10.1088/1674-1056/ad2dce

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Coupling of quasi-localized and phonon modes in glasses at low frequency

Jun Duan(段军)1,2, Song-Lin Cai(蔡松林)1,2, Gan Ding(丁淦)1, Lan-Hong Dai(戴兰宏)1,2, and Min-Qiang Jiang(蒋敏强)1,2,†   

  1. 1 State Key Laboratory of Nonlinear Mechanics, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, China;
    2 School of Engineering Science, University of Chinese Academy of Sciences, Beijing 101408, China
  • 收稿日期:2024-01-25 修回日期:2024-02-25 接受日期:2024-02-28 出版日期:2024-05-20 发布日期:2024-05-20
  • 通讯作者: Min-Qiang Jiang E-mail:mqjiang@imech.ac.cn
  • 基金资助:
    Project supported by the National Outstanding Youth Science Fund Project (Grant No. 12125206), the Fund from the Basic Science Center for “Multiscale Problems in Nonlinear Mechanics” (Grant No. 11988102), and the General Project of the National Natural Science Foundation of China (Grant No. 11972345).

Coupling of quasi-localized and phonon modes in glasses at low frequency

Jun Duan(段军)1,2, Song-Lin Cai(蔡松林)1,2, Gan Ding(丁淦)1, Lan-Hong Dai(戴兰宏)1,2, and Min-Qiang Jiang(蒋敏强)1,2,†   

  1. 1 State Key Laboratory of Nonlinear Mechanics, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, China;
    2 School of Engineering Science, University of Chinese Academy of Sciences, Beijing 101408, China
  • Received:2024-01-25 Revised:2024-02-25 Accepted:2024-02-28 Online:2024-05-20 Published:2024-05-20
  • Contact: Min-Qiang Jiang E-mail:mqjiang@imech.ac.cn
  • Supported by:
    Project supported by the National Outstanding Youth Science Fund Project (Grant No. 12125206), the Fund from the Basic Science Center for “Multiscale Problems in Nonlinear Mechanics” (Grant No. 11988102), and the General Project of the National Natural Science Foundation of China (Grant No. 11972345).

摘要: Boson peak of glasses, a THz vibrational excess compared to Debye squared-frequency law, remains mysterious in condensed-matter physics and material science. It appears in many different kinds of glassy matters and is also argued to exist in damped crystals. A consensus is that boson peak originates from the coupling of the (quasi)-localized non-phonon modes and the plane-wave-like phonon modes, but the coupling behavior is still not fully understood. In this paper, by modulating the content of localized modes and the frequencies of phonon modes, the coupling is clearly reflected in the localization and anharmonicity of low-frequency vibrational modes. The coupling enhances with increasing cooling rate and sample size. For finite sample size, phonon modes do not fully intrude into the low frequency to form a dense spectrum and they are not sufficiently coupled to the localized modes, thus there is no Debye level and boson peak is ill-defined. This suggestion remains valid in the presence of thermal motions induced by temperature, even though the anharmonicity comes into play. Our results point to the coupling of quasi-localized and phonon modes and its relation to the boson peak.

关键词: metallic glasses, low-frequency vibrational modes, plane wave, boson peak

Abstract: Boson peak of glasses, a THz vibrational excess compared to Debye squared-frequency law, remains mysterious in condensed-matter physics and material science. It appears in many different kinds of glassy matters and is also argued to exist in damped crystals. A consensus is that boson peak originates from the coupling of the (quasi)-localized non-phonon modes and the plane-wave-like phonon modes, but the coupling behavior is still not fully understood. In this paper, by modulating the content of localized modes and the frequencies of phonon modes, the coupling is clearly reflected in the localization and anharmonicity of low-frequency vibrational modes. The coupling enhances with increasing cooling rate and sample size. For finite sample size, phonon modes do not fully intrude into the low frequency to form a dense spectrum and they are not sufficiently coupled to the localized modes, thus there is no Debye level and boson peak is ill-defined. This suggestion remains valid in the presence of thermal motions induced by temperature, even though the anharmonicity comes into play. Our results point to the coupling of quasi-localized and phonon modes and its relation to the boson peak.

Key words: metallic glasses, low-frequency vibrational modes, plane wave, boson peak

中图分类号:  (Thermal properties of amorphous solids and glasses: heat capacity, thermal expansion, etc.)

  • 65.60.+a
62.20.D- (Elasticity) 62.25.Jk (Mechanical modes of vibration)