Freedericksz Transition Occurring in the Surface Induced Ordered State of a Nematic Liquid Crystal at the Temperature Just Above the Clearing Temperature

Abstract
Besides the normal Freedericksz transition attributing to the variation of the molecular conformation in the bulk region of a homogeneously aligned nematic liquid crystal, 5CB, which appears at the critical voltage Vc 1, the second Freedericksz transition has been observed at the voltage Vc 2 which is about 83 times larger than Vc 1 at the temperature just above the clearing point. This phenomenon was observed exclusively only in samples prepared by using the orientation layers of the rubbed polyimide or the Y- type Langmuir-Blodgett films comprising 31 stacking layers, but not with the films of the obliquely evaporated SiO films.