Observation of slow dynamics in an amorphous quasi-two-dimensional binary complex plasma

The first dedicated experimental study of slow dynamics in a quasi-2D complex plasma below melting temperature is reported. The experiments were performed in a GEC rf reference cell with an argon plasma. Binary mixture was introduced as a means to suppress crystallization and form a disordered particle suspension in equilibrium with two temperatures. Based on the particle dynamics, the self-part of the intermediate scattering function was calculated and the alpha-relaxation part of it was fitted by the Kohlrausch function. It reveals characteristic features of supercooled fluids approaching glassy state. The measured mean-squared displacement exhibits a crossover from the short-time ballistic dynamics to a transient subdiffusive behavior determined by collective interactions. We show that binary complex plasma is a suitable model system to study slow dynamics in supercooled fluids.