Experimental and ab initio molecular dynamics study of the structure and physical properties of liquid GeTe

Hans Weber, Mathias Schumacher, P. Jóvári, Yoshimi Tsuchiya, Werner Skrotzki, Riccardo Mazzarello, Ivan Kaban

Research output: Contribution to journalArticle

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Abstract

GeTe is a prototypical phase-change material employed in data storage devices. In this work, the atomic structure of liquid GeTe is studied by x-ray and neutron diffraction in the temperature range from 1197 to 998 K. The dynamic viscosity is measured from 1273 to 953 K, which is 55 K below the solidification point, using an oscillating-cup viscometer. The density of liquid GeTe between 1293 and 973 K is determined by the high-energy γ-ray attenuation method. The experiments are complemented with ab initio molecular dynamics (AIMD) simulations based on density functional theory (DFT). Compatibility of the AIMD-DFT models with the diffraction data is proven by simultaneous fitting of all data sets in the frame of the reverse Monte Carlo simulation technique. It is shown that octahedral order dominates in liquid GeTe, although tetrahedral structures are also present. The viscosity of the equilibrium and weakly undercooled liquid GeTe obeys the Arrhenius law with a small activation energy of the order of 0.3 eV, which is indicative of a highly fragile liquid. The calculated density of states and electronic wave functions point to the existence of a pseudogap and localized electron states within the gap in the equilibrium liquid near the melting point as well as in the undercooled liquid.

Original languageEnglish
Article number054204
JournalPhysical Review B
Volume96
Issue number5
DOIs
Publication statusPublished - Aug 10 2017

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Molecular dynamics
Physical properties
physical properties
molecular dynamics
Liquids
liquids
Density functional theory
Viscosity
Density of liquids
viscosity
density functional theory
Phase change materials
Viscometers
Neutron diffraction
Wave functions
phase change materials
viscometers
Electron energy levels
data storage
Melting point

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

Cite this

Experimental and ab initio molecular dynamics study of the structure and physical properties of liquid GeTe. / Weber, Hans; Schumacher, Mathias; Jóvári, P.; Tsuchiya, Yoshimi; Skrotzki, Werner; Mazzarello, Riccardo; Kaban, Ivan.

In: Physical Review B, Vol. 96, No. 5, 054204, 10.08.2017.

Research output: Contribution to journalArticle

Weber, Hans ; Schumacher, Mathias ; Jóvári, P. ; Tsuchiya, Yoshimi ; Skrotzki, Werner ; Mazzarello, Riccardo ; Kaban, Ivan. / Experimental and ab initio molecular dynamics study of the structure and physical properties of liquid GeTe. In: Physical Review B. 2017 ; Vol. 96, No. 5.
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