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arXiv · 1605.08157

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

Marco Malvestuto·Antonio Caretta·Barbara Casarin·Federico Cilento·Martina Dell'Angela·Daniele Fausti·Raffaella Calarco·Bart J. Kooi·Enrico Varesi·John Robertson·Fulvio Parmigiani
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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.

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Marco Malvestuto, Antonio Caretta, Barbara Casarin, Federico Cilento, Martina Dell'Angela, Daniele Fausti, Raffaella Calarco, Bart J. Kooi, Enrico Varesi, John Robertson, Fulvio Parmigiani. 2016-05-26. Insights into ultrafast Ge-Te bond dynamics in a phase-change superlattice. https://doi.org/10.1103/physrevb.94.094310

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