The possible role of growing static order in the dynamical slowing downtowards the glass transition has recently attracted considerable attention. Onthe basis of random first-order transition (RFOT) theory, a new method tomeasure the static correlation length of amorphous order, called "point-to-set(PTS)" length, has been proposed, and used to show that the dynamic lengthgrows much faster than the static length. Here we study the nature of the PTSlength, using a polydisperse hard disk system, which is a model that is knownto exhibit a growing hexatic order upon densification. We show that the PTScorrelation length is decoupled from the steeper increase of the correlationlength of hexatic order, while closely mirroring the decay length of two-bodydensity correlations. Our results thus provide a clear example that other formsof order can play an important role in the slowing down of the dynamics,casting a serious doubt on the order agnostic nature of the PTS length and itsrelevance to slow dynamics, provided that a polydisperse hard disk system is atypical glass former.
展开▼
