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Prof. Matthias Sperl, German Aerospace Center Köln, Germany

Glass-Glass-Transitions from Purely Repulsive Interactions
Wann 10.07.2019
von 14:15 bis 15:15
Wo Seminarraum A (1st floor), Freiburger Materialforschungszentrum (FMF)
Termin übernehmen vCal

In addition to the glass transition in the hard-sphere system, transitions between different amorphous solid states are known for systems with hard core plus short-ranged attraction. The dynamics in the vicinity of such glass-glass transitions have been worked out in detail in theory and tested in experiments and simulation. The established understanding of such transitions is given by a competition of repulsive and attractive length scales.
For the case of a competition between two repulsive length scales, the glass-transition scenarios are surprisingly rich: In addition to a reentry at constant packing fraction indicating melting by cooling, i.e., a sequence of glass-liquid-glass -- for increased pressure at constant temperature the sequence liquid-glass-liquid-glass is obtained which is corresponding to a diffusion anomaly in the liquid state. Beyond these reentry phenomena, not only one but two glass-glass transition lines are predicted and explained by the interplay of two different length scales.
Specific calculations are presented for a square-shoulder system and are considered relevant for colloidal suspensions, certain metals, and water.

Disconnected Glass-Glass Transitions and Diffusion Anomalies in a Model with Two Repulsive Length Scales, Phys. Rev. Lett. 104, 145701 (2010).
Multiple Glass Singularities and Isodynamics in a Core-Softened Model for Glass-Forming Systems, Phys. Rev. Lett. 113, 258302 (2014).