Magnetic-field-induced anisotropic curvature elasticity of a vesicle membrane containing magnetic polyions

Interaction between a charged membrane and the electrolyte solution containing magnetic polyions is considered. A self-magnetic field, which arises due to the nonhomogeneous magnetic particle distribution near a charged membrane increases the effective charge screening length for the parts of a membrane normal to a magnetic field. The anisotropy of elastic properties of a membrane depending on the screening length is calculated on the basis of the curvature expansion. It is shown that due to diminishing of the spontaneous curvature for the parts of a membrane normal to a magnetic field there are two competing mechanisms of the ferrovesicle shape transformation under the influence of a magnetic field—the formation of a prolate shape orientated along a field due to the diminishing action of the demagnetizing field energy and the deformation to a oblate shape due to the decrease in the spontaneous curvature of the parts of a membrane normal to a field.