Importance of density for phase-change materials demonstrated by ab initio simulations of amorphous antimony

Phase change materials (PCMs) serve as useful components in electronics and photonics. Here we demonstrate that various kinds of material properties of a PCM are significantly influenced by the realized mass density. Using ab initio simulations, we investigate supercooled-liquid antimony and the subsequent transition to a glassy phase. We observe a transition in the supercooled-liquid phase from an undistorted high-temperature to an increasingly Peierls-like distorted low-temperature phase. This transition also manifests in both the electronic density of states and optical properties. The strong dependence of these properties on mass density leads the way to explorations of property design for nanoconfined devices beyond the usual compositional modifications.