Quenching of phase coherence in quasi-one-dimensional ring crystals

Abstract

A comparison of the single-particle (SP) dynamics of whisker and ring $\mathrm{Nb}{\mathrm{Se}}_{3}$ crystals provides new insight into the phase transition properties of quasi-one-dimensional charge density wave (CDW) systems. In the incommensurate CDW phase, SP relaxation triggered by an ultrafast laser pulse reflects the formation of collective states, and reveals the divergence of the relaxation time when approaching a transition temperature. The degree of divergence is less pronounced in rings than in whiskers, suggesting a loss of phase coherence in ring crystals characterized by a closed-loop topology.