Crystal growth of Ge₂Sb₂Te₅ at high temperatures

Phase-change materials (PCMs) have important applications in optical and electronic storage devices. Ge₂Sb₂Te₅ (GST) is a prototypical phase-change material (PCM) employed in state-of-the-art storage-class memories. In this work, we investigate crystallization of GST at temperatures 600-800 K by ab initio molecular dynamics. We consider large models containing 900 atoms, which enable us to investigate finite-size effects by comparison with smaller models. We use the metadynamics method to accelerate the formation of a large nucleus and then study the growth of the nucleus by unbiased simulations. The calculated crystal growth speed and its temperature-dependent behavior are in line with recent experimental work.