Magnetic memory devices and systems

A method of storing one or more bits of information comprising: forming a magnetic bubble; and storing a said bit of information encoded in a typology of a domain wall of said magnetic bubble. Preferably a bit is encoded using a symmetric topological state of the domain wall and a topological state including at least one winding rotation of a magnetisation vector of the domain wall. Preferably the magnetic bubble is confined in an island of magnetic material, preferably of maximum dimension less than 1 μm.