Terahertz time-domain spectroscopic study on an oxide glass with entropic elasticity

For disordered systems, universal excitation called boson peak appears in the terahertz range. In addition, for polymeric glasses, fractal dynamics, so-called fracton, is expected to appear above boson peak frequency as a result of self-similarity of monomer unit. In this study, we performed terahertz time-domain spectroscopy on an oxide glass with entropic elasticity: mixed alkali metal metaphosphate glass with the chemical composition Li_0.25Na_0.25K_0.25Cs_0.25PO₃, to detect the boson peak and fracton. Obtained spectra are compared with results of low-frequency Raman scattering and low-temperature specific heat measurement.