Boson heat capacity peak and its evolution with the enthalpy state and defect concentration in a high entropy bulk metallic glass

We first measured the low temperature heat capacity of a high entropy bulk metallic glass in different enthalpy states created by preannealing. We found a boson heat capacity peak located at a temperature of ≈7 K with the height decreasing upon preannealing. Using the results of specially performed calorimetrical and shear modulus measurements and applying the Interstitialcy theory, we showed that the boson peak (BP) height increases linearly both with the excess enthalpy of glass determined calorimetrically and concentration of interstitial-type defects assumed responsible for the BP. The BP peak height and defect concentration are found smaller as compared with those in conventional metallic glasses based on a single element that is attributed to the high entropy state of the glass under investigation.