Low-dimensional glasses: Effect of occupational site disorder in the excess of low-frequency vibrational excitations

The present scientific case concerns a glass-forming system with even less degrees of freedom, namely the occupational disorder of high-temperature phase (I, P21/c) of para-Chloro-Nitro-benzene (p-CNB, C6H4ClNO2,) in which the occupational disorder (50:50 Cl:NO2 occupancy) involves rotation around a two-fold axis perpendicular to the plane of the molecules. We have already evidenced the dynamical glassy features of this phase as manifest by its thermal properties, namely specific heat and thermal conductivity, both displaying the excess within the Cp/T3 representation and the conductivity plateau, respectively. Our aim is to complement the measurements already carried out with data pertaining a fully ordered phase (II,P21) which we have been able to prepare and will therefore serve as an absolute reference.