Combined static potentials for confinement of neutral species

We discuss the general problem of generating confining potentials for neutral matter by combining different kinds of static forces. The interactions taken into account are those having a linear or quadratic dependence on the modulus of an irrotational and solenoidal field. Particular attention is devoted to the combination of electric and magnetic forces for paramagnetic species. In this case, tight confinement can be achieved by enhancing and balancing the field gradients. Combined potentials turn out to be conveniently generated by configurations based on high permeability materials. Feasibility of combined electric-magnetic traps and guides for neutral alkali-metal atoms is discussed