Structure of amorphous Cu2GeTe3 and the implications for its phase-change properties

Jens R. Stellhorn, Benedict Paulus, Shinya Hosokawa, Wolf Christian Pilgrim, Nathalie Boudet, Nils Blanc, Hiroyuki Ikemoto, Shinji Kohara, Yuji Sutou

Research output: Contribution to journalArticlepeer-review

Abstract

The structure of amorphous Cu2GeTe3 is investigated by a combination of anomalous X-ray scattering and extended X-ray absorption fine-structure experiments. The experimental data are analyzed with reverse Monte Carlo modeling, and they are interpreted in terms of short-range-order parameters as well as by using ring statistics and persistent homology to study the intermediate-range order. Based on this information, the structural relationship of the amorphous phase to the corresponding crystal is discussed. It is found that the amorphous network can be rationalized by small atomic displacements of the crystal structure, directed toward the intrinsic void regions. This structural similarity establishes the possibility of a fast phase-change process. On the other hand, the atomic rearrangements also lead to the formation of new chemical bonds and to distortions on the intermediate-range-order level. These are realized by a collapse and contraction of the strict hexagonal ring arrangements of the crystal and by the formation of small, triangular rings as well as Cu cluster configurations. These structural features allow for a new understanding of the phase-change property contrast of this material, especially concerning the density change and the optical contrast.

Original languageEnglish
Article number214110
JournalPhysical Review B
Volume101
Issue number21
DOIs
Publication statusPublished - 2020 Jun 1

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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