Institute of Industrial Science, University of Tokyo

1
Numerical and experimental evidence for static
signature of dynamic heterogeneity in supercooled
liquids
Institute of Industrial Science, University of
Tokyo Hajime Tanaka, Hiroshi Shintani, Takeshi
Kawasaki, and Keiji Watanabe
Dynamic Heterogeneity and Medium-range
Crystalline Order (MRCO)
Dynamic heterogeneity is considered to be a clue
to the mechanism of the liquid-glass transition,
but the physical origin of dynamic heterogeneity
has not been clarified. Recent numerical studies
and experiments demonstrated the existence of
medium-range crystalline order (MRCO) in
supercooled liquids, and suggested that MRCO may
be the origin of dynamic heterogeneity.
2D spin liquid (2DSL)
Driven Granular Matter as a Model System (2DGL)
Distribution of
Trajectory
????
1.0
0.8
0.6
0.4
0.2
H. Shintani and H. Tanaka, Nat. Phys. 2, 200
(2006).
0.0
2D polydiperse colloidal system (2DPC)
Fitting by 2D Ornstein-Zernike function
by T. Kawasaki et al.
T. Kawasaki, T. Araki H. Tanaka, PRL 99, 215701
(2007).
K.Watanabe H. Tanaka, PRL 100,158002 (2008).
Absence of static spatial density correlation
2DPC
2DGL
There is no indication of static density
correlation in S(q) in the region of q 1/?.
Instead, there are shoulders in the main peak
and splitting of the second peak. The fact that
MRCO does not accompany any density change means
that MRCO cannot be detected by the two-point
density correlator.
3DPC
2DSL
2DSL
2DPC
Relationship between MRCO and Dynamic
Heterogeneity
The Message of our work Contrary to the common
belief, we demonstrate that there is static
heterogeneity in an instantaneous structure of a
supercooled liquid, if we look it through the
proper order parameter, and it is the origin of
dynamic heterogeneity. However, since
medium-range crystalline order (MRCO) does not
accompany the density change, MRCO cannot be
detected by the static two-body density
correlator. We propose that slow dynamics is
caused by the critical-like divergence of MRCO
toward the ideal glass transition point. This
scenario suggests an intriguing link between
glass-transition and critical phenomena.