Observations of the Liquid-Crystal Analog of the Abrikosov Phase

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Science  09 Oct 1992:
Vol. 258, Issue 5080, pp. 275-278
DOI: 10.1126/science.258.5080.275


Freeze-fracture transmission electron micrographs of the smectic A* phase confirm the twist grain boundary model of Renn and Lubensky. The fracture surface has an undulating structure with a 0.5-micrometer helical pitch parallel to 4.1-nanometer smectic layers. The layers are disrupted by a lattice of screw dislocations oriented normal to the helical axis. Optical diffraction shows that rotation of smectic blocks occurs in discrete steps of about 17°; hence, the screw dislocations are 14 to 15 nanometers apart and the grain boundaries are 24 nanometers apart. These observations show that the SmA* phase is the liquid-crystal analog of the Abrikosov phase in superconductors.