The arrangement contains a second magnetic film, overlapping a first, and having a lower coercivity field strength than the first. A semiconducting film is provided between the magnetic films so that a photoinduced magnetisation occurs between them when the semiconducting film is exposed to light. The magnetic films have single-axis anisotropy in their planes. Each magnetised film is vertically magnetised. A third magnetic film can overlap the second magnetic film and with a coercivity field strength greater than that of the second film. A second semiconducting film can be arranged between the second and third magnetic films to induce magnetisation between them when illuminated
