Elasticity and behaviour under magnetic fields of cubic lyomesophases and smectic D liquid crystals

Abstract
We estimate the shear elastic constant in cubic liquid crystals such as D phases and cubic lyomesophases and find a value, which is about three orders of magnitude less than that of very soft atomic crystals (4He) and three orders of magnitude higher when compared with colloidal crystals. The behaviour under an external magnetic field is discussed and the importance of coupling terms to the order parameter, especially for cubic lyomesophases, is pointed out