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 ($T_g$). We demonstrate, using molecular dynamics results for Cu64Zr36, that this temperature, $T_A\approx 2\times T_g$, is linked with cooperative atomic rearrangements that produce domains of connected icosahedra. Supercooling to a new characteristic temperature, $T_D$, is shown to produce higher order cooperative rearrangements amongst connected icosahedra, leading to large-scale domain fluctuations and the onset of glassy dynamics. These extensive domains then abruptly stabilize above $T_g$ and eventually percolate before the glass is formed. All characteristic temperatures ($T_A$, $T_D$ and $T_g$) are thus connected by successive manifestations of the structural cooperativity that begins at $T_A$.

21 pages with 9 figures, Philosophical Magazine, 2016

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