B4 Exploring the impact of bonding on switching kinetics

In Project B4 (2019-2023), we plan to elucidate the relationship between structure, bonding and kinetics in phase change materials. For this purpose, we will employ various experimental tools (ultrafast calorimetry, optical tester) in combination with ab initio simulations and machine-learning methods. The main goals will be to link the ultrafast crystallization at high temperature and the relaxation of the amorphous state at low temperature to specific structural motifs and bonding mechanisms. We will also investigate the stability of ultrathin films of crystalline phase-change materials in relation to their bonding characteristics.


Disruption and formation of resonant bonds in phase-change materials: from aging of the amorphous phase to hidden states in the crystal (2015-2019)

Phase change materials exhibit extremely fast crystallization at high temperature, yet possess a stable amorphous phase at room temperature. In this combined experimental and computational work, we study the temperature dependence of the crystal growth velocity for different PC materials. Apparently, it differs significantly from good as well as marginal glass formers, such as elemental metals. Therefore, PC materials can provide new insights into understanding glass formation and fast crystallization. An investigation of aging processes in PC materials, as well as the consequences of the formation and rupture of resonant bonds will complement this study.

Crystallization kinetics in phase-change materials (2011-2015)

This project aims at an in-depth understanding of the unique crystallization kinetics that characterizes phase change materials. For this purpose, a combined experimental and computational investigation is being undertaken to elucidate the various aspects of the kinetic mechanisms. The crystal growth velocity is being measured for the first time over ten orders of magnitude by a laser tester. A new density functional theory molecular dynamics scheme is being employed to simulate crystallization processes in phase-change materials from first-principles. The insights provided by this combined study will help in the design of new phase change alloys with ultrafast crystallization and better switching properties.

Principal investigators:

Prof. Dr. rer. nat. R. Mazzarello
Institut für Theoretische Festkörperphysik
RWTH Aachen University
Phone: +49 (0)241 80 25722
E-mail: mazzarello@physik.rwth-aachen.de

Prof. Dr. rer. nat. M. Wuttig
I. Physikalisches Institut IA
RWTH Aachen University
Phone: +49 (0)241 80 27155
E-mail: wuttig@physik.rwth-aachen.de