A locally preferred structure characterises all dynamical regimes of a supercooled liquid

Abstract

Recent experimental results suggest that metallic liquids universally exhibit a high-temperature dynamical crossover, which is correlated with the glass transition temperature (). We demonstrate, using molecular dynamics results for , that this temperature, , is linked with cooperative atomic rearrangements that produce domains of connected icosahedra. Supercooling to a new characteristic temperature, , is shown to produce higher order cooperative rearrangements amongst connected icosahedra, which manifests as the formation of large Zr-rich connected domains that possess macroscopic proportions of the liquid’s icosahedra. This coincides with the decoupling of atomic diffusivities, large-scale domain fluctuations and the onset of glassy dynamics in the liquid. These extensive domains then abruptly stabilise above and eventually percolate before the glass is formed. All characteristic temperatures (, and ) are thus connected by successive manifestations of the structural cooperativity that begins at .

Keywords:

• Supercooled liquids
• metallic glasses
• molecular dynamic simulations

Acknowledgements

Fruitful discussions with Takeshi Egami are gratefully acknowledged. ZN is grateful to the Feinberg foundation for visiting faculty program at the Weizmann Institute. The computational resources have been provided by the Lonestar and Stampede of Teragrid at the Texas Advanced Computing Center (TACC) and the Edison cluster of the National Energy Research Scientific Computing Center (NERSC). All plots were made using the matplotlib Python library [55].

Notes

No potential conflict of interest was reported by the authors.

Additional information

Funding

RS, VT and LY are supported by the National Science Foundation (NSF) [grant number DMR-1207141]; KFK is supported by NSF [grant number DMR-12-06707]; ZN is supported by NSF [grant number DMR-1106293] and [grant number DMR-141122].