Roles of growing structural order in slow glassy dynamics and crystal nucleation

Condensed Matter lunchtime seminar

Roles of growing structural order in slow glassy dynamics and crystal nucleation

  • Event time: 2:00pm
  • Event date: 14th July 2015
  • Speaker: Hajime Tanaka (Institute of Industrial Science, University of Tokyo, Meguro-ku, Tokyo 153-8505, Japan)
  • Location: Lecture Theatre C,

Event details

The origin of dynamical slowing down towards glass transition is one of the most fundamental unsolved problems in condensed matter physics. Recently roles of growing static order in dynamical slowing down have attracted considerable attention. The random-first-order-transition (RFOT) scenario predicts that the dynamic length grows much faster than the static length. Contrary to this scenario, we find a close link between dynamical and static length for some systems such as polydisperse particle systems and spin liquids [1]. Here we study the nature of the point-to-set (PTS) length, using a polydisperse hard disk system, which is a model that exhibits a growing hexatic order upon densification. The results show that the PTS correlation length closely mirrors the decay length of two-body density correlation, while being decoupled from the steeper increase of the correlation length of hexatic order [2]. This casts a serious doubt on the order agnostic nature of the PTS length and its relevance to slow dynamics at least for our system. Our study shows that in the polydisperse systems, slow dynamics is linked to the growth of bond orientational order rather than that of the PTS length. We also find that this growth of static structural order also acts as precursors for crystal nucleation [1,3]. In a few systems, we reveal that breakdown of local rotational symmetry in a supercooled liquid induces nucleation of a crystal having the same symmetry. These findings suggests that we need to consider structural ordering (or, many-body correlations) such as bond orientational ordering in addition to translational ordering for describing a high-density liquid state.

REFERENCES

[1] H. Tanaka, Eur. Phys. J E, 35, 113 (2012). [2] J. Russo and H. Tanaka, PNAS 112, 6920 (2015). [3] T. Kawasaki and H. Tanaka, PNAS 107, 14036 (2010), J. Phys.: Condens. Matter 22, 232102 (2010); J. Russo and H. Tanaka, Sci Rep. 2, 505 (2012), Soft Matter 8, 4206 (2012); J. Russo, F. Romano and H. Tanaka, Nature Mater. 13, 733 (2014), unpublished.

This is a weekly series of informal talks given primarily by members of the soft condensed matter and statistical mechanics groups, but is also open to members of other groups and external visitors. The aim of the series is to promote discussion and learning of various topics at a level suitable to the broad background of the group. Everyone is welcome to attend..

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