Anticonical anchoring and surface transitions in a nematic liquid crystal.

Recent works reported planar and conical azimuthally degenerated nematic anchorings. Here we predict an additional ``anticonical'' degenerated anchoring. Its energy presents two minima, parallel and perpendicular to the substrate plane, separated by a conical energy barrier. We realize this bistable anchoring on a grafted polymer brush and we observe temperature-driven transitions between the conical, planar, and anticonical degenerated anchorings. Under electric field we break the anticonical anchoring and switch between its bistable states.