The application of amorphous chalcogenide alloys as data-storage media relies on their ability to undergo an extremely fast (10-100 ns) crystallisation once heated at sufficiently high temperature. However, the peculiar features that make these materials so attractive for memory devices still lack a comprehensive microscopic understanding. By means of large scale molecular dynamics simulations, we demonstrate that the supercooled liquid of the prototypical compound GeTe shows a very high atomic mobility (D \sim 10^(-6) cm2/s) down to temperatures close to the glass transition temperatures. This behaviour leads to a breakdown of the Stokes-Einstein relation between the self- diffusion coefficient and the viscosity in the supercooled liquid. The results suggest that the fragility of the supercooled liquid is the key to understand the fast crystallisation process in this class of materials.
Viscosity, breakdown of Stokes-Einstein relation and dynamical heterogeneity in supercooled liquid Ge$_2$Sb$_2$Te$_5$ from simulations with a neural network potential
Breakdown of material-time scaling in the microscopic dynamics of metallic glasses
Institute of Frontier Materials on Earth and in Space, German Aerospace Center（地球与太空前沿材料研究所，德国航空航天中心）；Institut Néel, Université Grenoble Alpes and Centre National de la Recherche Scientifique（内尔研究所，格勒诺布尔阿尔卑斯大学及法国国家科学研究中心）；European Synchrotron Radiation Facility（欧洲同步辐射装置）；Institute for Condensed Matter Physics, Technical University of Darmstadt（凝聚态物理研究所，达姆施塔特工业大学）；Department of Physics, Institute of Energy Technologies, Universitat Politècnica de Catalunya—BarcelonaTech（物理系，能源技术研究所，加泰罗尼亚理工大学）
