Periodic distortions near the Fredericks threshold in nematic liquid crystals

The present work studies the behavior of one-dimensional periodic magnetic walls in the neighborhood of the Fredericks threshold of a nematic liquid crystal sample. The results show that in this region there is a linear relation between the inverse of the length of these walls and the square of the magnetic field, whose coefficients depend only on the elastic constants. This relation is verified experimentally and it is used to determine the ratio between the bend elastic constant and the diamagnetic susceptibility anisotropy of a lyotropic nematic sample composed of potassium laurate, potassium chloride and water. (C) 1998 Elsevier Science B.V.