Femtosecond x-ray diffraction reveals a liquid–liquid phase transition in phase-change materials

Research output: Contribution to journalArticle


In phase-change memory devices, a material is cycled between glassy and crystalline states. The highly temperature-dependent kinetics of its crystallization process enables application in memory technology, but the transition has not been resolved on an atomic scale. Using femtosecond x-ray diffraction and ab initio computer simulations, we determined the time-dependent pair-correlation function of phase-change materials throughout the melt-quenching and crystallization process. We found a liquid–liquid phase transition in the phase-change materials Ag4In3Sb67Te26 and Ge15Sb85 at 660 and 610 kelvin, respectively. The transition is predominantly caused by the onset of Peierls distortions, the amplitude of which correlates with an increase of the apparent activation energy of diffusivity. This reveals a relationship between atomic structure and kinetics, enabling a systematic optimization of the memory-switching kinetics.


  • Peter Zalden
  • Florian Quirin
  • Mathias Schumacher
  • Jan Siegel
  • Shuai Wei
  • Azize Koc
  • Matthieu Nicoul
  • Mariano Trigo
  • Pererik Andreasson
  • Michael J. Shu
  • Tommaso Pardini
  • Matthieu Chollet
  • Diling Zhu
  • Henrik Lemke
  • Ider Ronneberger
  • Aaron M. Lindenberg
  • Henry E. Fischer
  • Stefan Hau-Riege
  • David A. Reis
  • Riccardo Mazzarello
  • Matthias Wuttig
  • Klaus Sokolowski-Tinten
External organisations
  • Stanford Linear Accelerator Center (SLAC)
  • European XFEL GmbH
  • University of Duisburg-Essen
  • RWTH Aachen University
  • CSIC - Instituto de Óptica Daza de Valdés; (IO-CSIC)
  • University of Potsdam
  • Stanford University
  • Lawrence Livermore National Laboratory
  • Paul Scherrer Institute
  • Institut Laue Langevin
  • Jülich Research Centre
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Condensed Matter Physics
  • Materials Chemistry
Original languageEnglish
Pages (from-to)1062-1067
Number of pages6
Issue number6445
Publication statusPublished - 2019
Publication categoryResearch