Anisotropic Ultrasound Propagtion in a Semctic- C Liquid Crystal

Abstract

We report here the results of longitudinal ultrasound propagation in a magnetically aligned smećtic-C liquid crystal (p-ṕ Heptyloxyazozy benezene). In the sectic-C phase the plane normals can lie anywhere on a cone with the axis along the magnetic field direction in which the sample ws cooled. The effects of the layer normal direction and the molecular orientation within the planes on the velocity anisotropy were separatedby cooling the sample into th smectic-C phase at particular orientations of the magnetic field and subsequently rotating the magnetic field. The results were analyzed on the basis of a multidomain model where the azimuthal angle of the plane normal around the field direction was averaged over.