Novel anomalies of soft quasi-localized glassy mode in the vicinity of boson peak frequency

We did Raman spectroscopy on Bench mark Glassy compositions and investigate soft quasi-localized modes. Science of this quasi-localized glassy mode in the vicinity of boson peak is still in developing stage due to availability of few experimental data. Vibrational density of states (G(w)) have obtained from the low frequency spectrum on three key compositions which represent three distinct dependence of power law (G(w) similar to w(2.22), w(3.44) and w(3.09)) while boson peak usually shows only behavior of G(w) similar to w(2).On the basis of analysis we are formulating a general law G(w)similar to(d+n) where d = 2 (Debye nature) and n is an integer/fractional, physical meaning of n is deviation from the Debye behavior is directly correlated to stability of glass, larger is the value of n corresponds to measure of ultra-high stability of the glass. On increasing germanium concentration in selenium matrix, changes its network connectivity. Characterization of Acoustic vibrational modes (Ge15Se85, Ge20Se80 and Ge33Se67) provide us resonance peak frequency (wr) which shifts towards low frequency side with an increasing networking concentration, respectively, 14.22 cm(-1), 12.69 cm(-1) and 9.7338 cm(-1) have been noticed. Quasi-localized vibrations shows relaxation in decaying density of states is identified as fast beta process which are purely exponential. Damping nature of these acoustic modes are discussing in terms of under damping, critical damping and over damping for corresponding sample.

Automated summary

We performed Raman spectroscopy on benchmark glassy compositions and investigated soft quasi-localized modes. The study of these quasi-localized modes in the vicinity of the boson peak is still in its early stages due to limited experimental data. We obtained the vibrational density of states using the low-frequency spectrum for three key compositions, which showed different power law dependencies (G(w) similar to w(2.22), w(3.44), and w(3.09)), while the boson peak typically exhibited a G(w) similar to w(2) behavior. Based on our analysis, we are formulating a general law, G(w) similar to (d+n), where d=2 (Debye nature) and n is an integer/fractional value that represents the deviation from Debye behavior and directly correlates with the stability of the glass. The increase in germanium concentration in the selenium matrix results in changes in the network connectivity. Acoustic vibrational modes characterization (Ge15Se85, Ge20Se80, and Ge33Se67) revealed a shift towards lower frequencies with increasing networking concentration, with resonance peak frequency (wr) values of 14.22 cm(-1), 12.69 cm(-1), and 9.7338 cm(-1), respectively. The relaxation in the decaying density of states of quasi-localized vibrations was identified as a fast beta process with purely exponential decay. The damping nature of these acoustic modes was discussed in terms of under damping, critical damping, and over damping for the corresponding samples.