Dislocation reactions, grain boundaries, and irreversibility in two-dimensional lattices using topological tweezers

作者：Irvine William T M^*; Hollingsworth Andrew D; Grier David G; Chaikin Paul M

来源：Proceedings of the National Academy of Sciences of the United States of America, 2013, 110(39): 15544-15548.

DOI：10.1073/pnas.1300787110

• topological defect
• colloidal crystal
• holographic trapping

Dislocations, disclinations, and grain boundaries are topological excitations of crystals that play a key role in determining out-of-equilibrium material properties. In this article we study the kinetics, creation, and annihilation processes of these defects in a controllable way by applying "topological tweezers," an array of weak optical tweezers which strain the lattice by weakly pulling on a collection of particles without grabbing them individually. We use topological tweezers to deterministically control individual dislocations and grain boundaries, and reversibly create and destroy dislocation pairs in a 2D crystal of charged colloids. Starting from a perfect lattice, we exert a torque on a finite region and follow the complete step-by-step creation of a disoriented grain, from the creation of dislocation pairs through their reactions to form a grain boundary and their reduction of elastic energy. However, when the grain is rotated back to its original orientation the dislocation reactions do not retrace. Rather, the process is irreversible; the grain boundary expands instead of collapsing.

• 出版日期2013-9-24