title: Aging mechanisms in amorphous phase-change materials.
abstract: Aging is a ubiquitous phenomenon in glasses. In the case of phase-change materials, it leads to a drift in the electrical resistance, which hinders the development of ultrahigh density storage devices. Here we elucidate the aging process in amorphous GeTe, a prototypical phase-change material, by advanced numerical simulations, photothermal deflection spectroscopy and impedance spectroscopy experiments. We show that aging is accompanied by a progressive change of the local chemical order towards the crystalline one. Yet, the glass evolves towards a covalent amorphous network with increasing Peierls distortion, whose structural and electronic properties drift away from those of the resonantly bonded crystal. This behaviour sets phase-change materials apart from conventional glass-forming systems, which display the same local structure and bonding in both phases.
authors.affiliation: Physics of Solids Interfaces and Nanostructures, B5, Université de Liège, B4000 Sart-Tilman, Belgium.
authors.forename: Jean Yves
authors.initials: JY
authors.lastname: Raty
authors.affiliation: 1] I. Institute of Physics (IA), RWTH Aachen University, 52056 Aachen, Germany [2] Institute for Theoretical Solid State Physics, RWTH Aachen University, 52056 Aachen, Germany.
authors.forename: Wei
authors.initials: W
authors.lastname: Zhang
authors.affiliation: 1] I. Institute of Physics (IA), RWTH Aachen University, 52056 Aachen, Germany [2] Faculté des Sciences, de la Technologie et de la Communication, University of Luxembourg, Luxembourg City, L-1511, Luxembourg.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Luckas
authors.affiliation: I. Institute of Physics (IA), RWTH Aachen University, 52056 Aachen, Germany.
authors.forename: Chao
authors.initials: C
authors.lastname: Chen
authors.affiliation: 1] Institute for Theoretical Solid State Physics, RWTH Aachen University, 52056 Aachen, Germany [2] JARA FIT and JARA HPC, RWTH Aachen University, 52062 Aachen, Germany.
authors.forename: Riccardo
authors.initials: R
authors.lastname: Mazzarello
authors.affiliation: Centre Interdisciplinaire de Nanoscience de Marseille (CINaM), Aix-Marseille University and CNRS, Campus de Luminy, Case 913, F13288 Marseille, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Bichara
authors.affiliation: 1] I. Institute of Physics (IA), RWTH Aachen University, 52056 Aachen, Germany [2] JARA FIT and JARA HPC, RWTH Aachen University, 52062 Aachen, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Wuttig