Observation of the Pinning-Induced Crystal-Hexatic-Glass Transition in Two-Dimensional Colloidal SuspensionsSupported by the National Natural Science Foundation of China (Grant Nos. 12074275, 11704269, and 11704270), the Natural Science Foundation of the Jiangsu Higher Education Institutions of China (Grant Nos. 20KJA150008 and 17KJB140020), and the PAPD Program of Jiangsu Higher Education Institutions.

Abstract

Identification of the glass formation process in various conditions is of importance for fundamental understanding of the mechanism of glass transitions as well as for developments and applications of glassy materials. We investigate the role of pinning in driving the transformation of crystal into glass in two-dimensional colloidal suspensions of monodisperse microspheres. The pinning is produced by immobilizing a fraction of microspheres on the substrate of sample cells where the mobile microspheres sediment. Structurally, the crystal-hexatic-glass transition occurs with increasing the number fraction of pinning ρ pinning, and the orientational correlation exhibits a change from quasi-long-range to short-range order at ρ pinning = 0.02. Interestingly, the dynamics shows a non-monotonic change with increasing the fraction of pinning. This is due to the competition between the disorder that enhances the dynamics and the pinning that hinders the particle motions. Our work highlights the important role of the pinning on the colloidal glass transition, which not only provides a new strategy to prevent crystallization forming glass, but also is helpful for understanding of the vitrification in colloidal systems.