Soft Matter and Biophysics Seminar: 2D Colloidal Crystals with Anisotropic Impurities

The Department of Physics is pleased to welcome Prof. Xinsheng Sean Ling for a Soft Matter and Biophysics Seminar virtual presentation. Professor Ling is a Professor of Physics at Brown University, with particular expertise and interest in the areas of  Colloid Physics, Nanobiophysics, Quantum Physics of Matter, and Superconducting Wire Networks. 

Abstract:

We report a study [1] of 2D colloidal crystals with anisotropic ellipsoid impurities using video microscopy. It is found that at low impurity densities, the impurity particles behave like floating disorder with which the quasi-long-range orientational order  survives and the elasticity of the system is actually enhanced. There is a critical impurity density above which the 2D crystal loses the quasi long-range orientational order. At high impurity densities, the 2D crystal breaks into polycrystalline domains separated by grain boundaries where the impurity particles aggregate. This transition is accompanied by a decrease in the elastic moduli, and it is associated with strong heterogeneous dynamics in the system.  The correlation length vs. impurity density in the disordered phase exhibits an essential singularity at the critical impurity density.  This work was a collaboration with Prof. Zexin Zhang’s group in Soochow University, Suzhou, China, and it was funded by the NNSFC in China.

[1] Ya Chen, Xinlan Tan, Huaguang Wang, Zexin Zhang, J. M. Kosterlitz, X. S. Ling, “2D Colloidal Crystals with Anisotropic Impurities”, Phys. Rev. Lett. 127, 018004 (2021)