Low temperature heat capacity and sound velocity in fullerite C₆₀ orientational glasses

The nature of the linear term in the heat capacity of fullerite C₆₀ has been investigated. The low-temperature dependence of the sound velocity has been determined from the data of the heat capacity at temperatures below 4 K. A model of the dynamic configuration excitations (DCE) is proposed to describe the contribution of the linear term in heat capacity and calculate the dependence of sound velocity. It is shown that this model, apparently, adequately describes the dynamics of cluster formations of the short-range order in fullerite C₆₀ by taking into account excitations of both the atomic and electronic subsystems. In the framework of this model, it is shown that low-energy tunnel states that are located at the boundaries of C₆₀ domains make a dominant contribution to the low-temperature effects in the heat capacity and sound velocity of C₆₀.