Crossovers in the dynamics of supercooled liquids probed by an amorphous wall

Glen M Hocky (1) , Ludovic Berthier (2) , Walter Kob (2) , David R. Reichman (1)

1 Columbia University [New York]
2 L2C - Laboratoire Charles Coulomb

We study the relaxation dynamics of a binary Lennard-Jones liquid in the presence of an amorphous wall generated from equilibrium particle configurations. In qualitative agreement with the results presented in Nature Phys. {\bf 8}, 164 (2012) for a liquid of harmonic spheres, we find that our binary mixture shows a saturation of the dynamical length scale close to the mode-coupling temperature $T_c$. Furthermore we show that, due to the broken symmetry imposed by the wall, signatures of an additional change in dynamics become apparent at a temperature well above $T_c$. We provide evidence that this modification in the relaxation dynamics occurs at a recently proposed dynamical crossover temperature $T_s > T_c$, which is related to the breakdown of the Stokes-Einstein relation. We find that this dynamical crossover at $T_s$ is also observed for a system of harmonic spheres as well as a WCA liquid, showing that it may be a general feature of glass-forming systems.

Domaines: Mécanique statistique [cond-mat.stat-mech]; Matière Molle [cond-mat.soft]

Glen M Hocky, Ludovic Berthier, Walter Kob, David R. Reichman. Crossovers in the dynamics of supercooled liquids probed by an amorphous wall. Physical Review E : Statistical, Nonlinear, and Soft Matter Physics, 2014, 89, pp.052311. ⟨10.1103/PhysRevE.89.052311⟩. ⟨hal-00998409⟩