Glassy thermal anomalies due to dipolar reorientations? Specific heat ofN2-Ar-CO alloys

Abstract

It has been previously proposed that the excess low-temperature specific heat of the orientational glass KCN-KBr is due to dipolar (π) reorientations. To test this assertion, we have prepared related orientational glasses ${\mathrm{N}}_2$-Ar-CO in which the relative concentrations of asymmetric CO and symmetric ${\mathrm{N}}_2$ may be varied. The low-temperature specific-heat measurements on ${\mathrm{N}}_2$-Ar-CO reported here for temperatures between 0.15 and 4 K demonstrate that the asymmetric CO molecules are not important to the excess heat capacity.