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Igor Aronson2 Mikhail Genkin1 Andrey Sokolov3

2, The Pennsylvania State University, University park, Pennsylvania, United States
1, Northwestern University, Evanston, Illinois, United States
3, Argonne National Laboratory, Argonne, Illinois, United States

Living nematic is a realization of active matter combining a nematic liquid crystal with swimming bacteria. The material exhibits a remarkable tendency towards spatiotemporal self-organization manifested in the formation of dynamic textures of self-propelled half-integer topological defects (disclinations).This living nematic demonstrates the coexistence of isotropic and nematic domains, or tactoids, in a certain range of temperatures. Our computational study and dedicated experiment revealed how the tactoids control organization of living nematic by targeting singularities in molecular alignment, or topological defects. We have established that tactoid's I-N interface spontaneously acquire negative topological charge which is proportional to the tactoid's size and depends on the concentration of bacteria. The observed negative charging is attributed to the drastic difference in the mobilities of 1/2 and -1/2 topological defects in active systems.The results hint into new strategies for control of active matter.

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