| dc.description.abstract |
Under weak external stress, intermittent emergent responses in the form of avalanche type spatiotemporal clusters are ubiquitous phenomena in strongly coupled systems, such as granular systems, stressed solids, and seismic systems. The strong coupling not only sustains the structure from structural rearrangement but also spreads the local strain energy to remote regions inducing spatiotemporally correlated clusters once the accumulated local strain energy goes beyond a certain threshold.
Unlike solids, under weak external stress, liquids exhibit plastic deformation. The local strain energy cannot accumulate and is rapidly relaxed through structural rearrangement. However, unlike the intuitive expectation, a cold liquid around freezing under weaker thermal agitations is not completely disordered. It possesses a patchwork of crystalline ordered domains (CODs), which not only sustains the local strain energy but also releases the energy through structural rearrangement. Recent studies showed that the thermal-excited structural rearrangement exhibits cooperative excitation hopping in the form of co-rotating CODs, which ruptures the large CODs into small CODs followed by healing back to large CODs, and that, under weak external stress, CODs can temporarily sustain and propagate the local stress to remote regions that further initiates the bond cracking near defects. Nevertheless, the generic spatiotemporal dynamics, the scaling behaviors and the kinetic classification of the cracking, and the alarms for warning the short quiescent period between cracking bursts, are still unexplored issues.
In this work, we experimentally investigate spatiotemporal dynamical behaviors of the avalanche type structural rearrangement through cracking-healing processes in a weakly stressed dusty plasma cold liquid. It is found that the cracking cluster size in xyt space follows power law distribution. The histograms of the cracking burst and quiescent time periods between cracking, and the persistent times maintaining ordered and disordered structures all follow power law scaling behaviors. The temporal cracking behavior can be classified into single burst and successive cracking burst fluctuation. Kinetically, a COD is ruptured by cracking lines through co-rotating domains, which induce dislocation propagation into the region. If the directions of the Burgers vectors of incoming dislocations allow dislocation annihilation, deteriorated structure anneals into a large COD. If the directions of Burgers vectors forbid the annihilation process, the structure needs successive cracking behavior to resume a better structural order. The low regional structural order at the end of a cracking burst can be regarded as an alarm for predicting a short quiescent time period before the next cracking burst. | en_US |