This title appears in the Scientific Report :
2014
Please use the identifier:
http://hdl.handle.net/2128/8134 in citations.
Please use the identifier: http://dx.doi.org/10.1103/PhysRevB.90.184109 in citations.
Simulation of crystallization in ${\mathrm{Ge}}_{2}{\mathrm{Sb}}_{2}{\mathrm{Te}}_{5}$: A memory effect in the canonical phase-change material
Simulation of crystallization in ${\mathrm{Ge}}_{2}{\mathrm{Sb}}_{2}{\mathrm{Te}}_{5}$: A memory effect in the canonical phase-change material
Crystallization of amorphous Ge2Sb2Te5 (GST) has been studied using four extensive (460 atoms, up to 4 ns) density functional/molecular dynamics simulations at 600 K. This phase change material is a rare system where crystallization can be simulated without adjustable parameters over the physical ti...
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Personal Name(s): | Kalikka, J. (Corresponding Author) |
---|---|
Akola, J. / Jones, R. O. | |
Contributing Institute: |
Quanten-Theorie der Materialien; IAS-1 Quanten-Theorie der Materialien; PGI-1 |
Published in: | Physical Review B Physical review / B, 90 90 (2014 2014) 18 18, S. 184109 184109 |
Imprint: |
College Park, Md.
APS
2014
|
DOI: |
10.1103/PhysRevB.90.184109 |
Document Type: |
Journal Article |
Research Program: |
Spin-based and quantum information |
Link: |
OpenAccess |
Publikationsportal JuSER |
Please use the identifier: http://dx.doi.org/10.1103/PhysRevB.90.184109 in citations.
Crystallization of amorphous Ge2Sb2Te5 (GST) has been studied using four extensive (460 atoms, up to 4 ns) density functional/molecular dynamics simulations at 600 K. This phase change material is a rare system where crystallization can be simulated without adjustable parameters over the physical time scale, and the results could provide insight into order-disorder processes in general. Crystallization is accompanied by an increase in the number of ABAB squares (A:Ge,Sb;B:Te), percolation, and the occurrence of low-frequency localized vibration modes. A sample with a history of order crystallizes completely in 1.2 ns, but ordering in others was less complete, even after 4 ns. The amorphous starting structures without memory display phases (>1ns) with subcritical nuclei (10–50 atoms) ranging from nearly cubical blocks to stringlike configurations of ABAB squares and AB bonds extending across the cell. Percolation initiates the rapid phase of crystallization and is coupled to the directional p-type bonding in metastable GST. Cavities play a crucial role, and the final ordered structure is distorted rock salt with a face-centered cubic sublattice containing predominantly Te atoms. We comment on earlier models based on smaller and much shorter simulations. |