Insights into ultrafast Ge-Te bond dynamics in a phase-change superlattice

TL;DR

This study uses time-resolved X-ray absorption spectroscopy and first-principles modeling to investigate ultrafast lattice relaxation and bond dynamics in a Ge-Te phase-change superlattice, revealing atomistic insights into cooling mechanisms.

Contribution

It introduces a novel experimental approach combining tr-XAS with first-principles modeling to understand ultrafast phase-change dynamics at the atomic level.

Findings

Atomistic insight into lattice relaxation post-ultrafast heating

First-principles model accurately reproduces observed dynamics

Potential application in studying structural strain effects

Abstract

A long-standing question for avant-grade data storage technology concerns the nature of the ultrafast photoinduced phase transformations in the wide class of chalcogenide phase-change materials (PCMs). Overall, a comprehensive understanding of the microstructural evolution and the relevant kinetics mechanisms accompanying the out-of-equilibrium phases is still missing. Here, after overheating a phase-change chalcogenide superlattice by an ultrafast laser pulse, we indirectly track the lattice relaxation by time resolved X-ray absorption spectroscopy (tr-XAS) with a sub-ns time resolution. The novel approach to the tr-XAS experimental results reported in this work provides an atomistic insight of the mechanism that takes place during the cooling process, meanwhile a first-principles model mimicking the microscopic distortions accounts for a straightforward representation of the observed dynamics. Finally, we envisage that our approach can be applied in future studies addressing the role of dynamical structural strain in phase-change materials.