Basic collective excitations in the melting transition of 2D Yukawa solids

Yen Chiu^1*, Yun-Xuan Zhang¹, Hao-Wei Hu¹, Lin I¹

¹Department of Physics, National Central University, Jhongli, Taiwan

* Presenter:Yen Chiu, email:yenychiu0322@gmail.com

According to the KTHNY (Kosterlitz-Thouless-Halperin-Nelson-Young) theory, the melting transition from 2D solids to liquids is a smooth transition through the intermediate hexatic phase, associated with the emergence of thermally excited free dislocation defects which causes the loss of long range translational order but not the orientational order. In this work, we numerically investigate the basic collective excitations for generating free-dislocation defects and defect clusters, and their associated spatiotemporal behaviors in the hexatic phase of a 2D Yukawa system through molecular dynamic simulation. It is found that the thermally excited small-scale collective particle motions can distort the local ordered structure, which plays the key role for the observed cascaded generation, dissociation, propagation, recombination, and annihilation of free dislocation defects. It also causes the formation of ring- or string-like defect clusters surrounding the small crystalline ordered domains with different lattice orientations.

Keywords: Yukawa system, 2D melting transition, Free dislocations