Effect of electric and magnetic fields on current-voltage characteristics of a lyotropic liquid crystal

The effect of electric and magnetic fields on current-voltage characteristics is studied for the lamellar phase in the lyotropic liquid-crystal sodium pentadecylsulfonate (SPDS) - water and lecithin - water systems. It has been found that the current-voltage characteristics of both systems have hysteresis. In the case of ionogenic SPDS, the hysteresis is formed due to ion current caused by the spatial reorientation of domains consisting of parallel lamellar fragments; in the case of lecithin, whose molecules contain dipoles, the hysteresis is formed due to the spatial reorientation of domains caused by the interaction of the resultant dipole moment of the domains with the electric field. It is shown that the introduction into lamellae of cetylpyridine bromide, which has an intrinsic magnetic moment, changes the resultant magnetic moment of domains and, thus, also the hysteresis loop of the current-voltage characteristic. The systems studied show the ''memory'' effect with respect to both the electric and magnetic fields. Field-induced processes of domain reorientation were recorded by the method of small-angle X-ray scattering.