Surface alignment bistability of nematic liquid crystals by orientationally frustrated surface patterns

We demonstrate a robust in-plane bistability of liquid-crystal surface alig nment based on tailored submicrometer-sized surface domains imposing a frus trated alignment. By a nanorubbing technique utilizing the atomic force mic roscope, we prepared an orientational checkerboard pattern on polyimide lay er, consisting of square unit domains on which the alignment is locally con strained to be planar yet orthogonal between the neighboring domains. Due t o the four-fold rotational symmetry of the pattern, the two diagonal axes o f the square domain become equally stable directions for the macroscopic li quid crystal alignment. The alignment could be switched between these two s tates by an in-plane electric field above a certain threshold, determined b y the local azimuthal anchoring. (C) 2001 American Institute of Physics.