Modeling of low-temperature specific heat data for Ge27As13S60 and As40S60 glasses by means of the phenomenologically modified soft potential model

Experimental results for the low-temperature specific heat C_p of Ge₂₇As₁₃S₆₀ and As₄₀S₆₀ glasses, measured from 70 K down to 0.54 K, are presented. A maximum in the temperature dependence of the scaled specific heat C_p/T³, appearing in the Boson peak range 2-10 K, and a minimum of this quantity in the tunneling-state range below 1 K, typical for all the glassy materials, were obtained. The presented C_p data are modeled in the frames of a phenomenologically modified soft potential model, applicable in wide low-temperature range. The character of the low-energy excitations in the investigated Ge-As chalkogenides is clarified.