Abstract: A magnetic element comprises a closed loop of ferromagnetic material having an even number of magnetic domains of opposite sense. The magnetisation within the domains is in a circumferenial direction, and the domains have leading and trailing walls extending from the inside to the outside of this loop. The magnetic element has a geometry such that there are at least two stable equilibrium domain configurations in which the domain walls are confined in predetermined portions of the loop and wherein the element is switchable between the stable configurations upon the application of a external magnetic field.