double exchange is a related magnetic coupling interaction proposed by clarence zener to account for electrical transport properties. it differs from superexchange in the following manner: in superexchange, the occupancy of the d-shell of the two metal ions is the same or differs by two, and the electrons are localized. for other occupations (double exchange), the electrons are itinerant (delocalized); this results in the material displaying magnetic exchange coupling as well as metallic conductivity.