The illustration shows the process of fabricating lateral spin valves. Left: Initially, the alloy's structure is highly ordered. Iron atoms (blue) and aluminium atoms (white) are arranged in continuous layers. Center: Ion bombardment (red) upsets the order leading to a random distribution of atoms. Only narrow stripes that are coated with a protective polymer resist are spared, and retain their atomic ordering. Right: Ion-irradiated regions become ferromagnetic. With the help of an externally applied magnetic field, the stripes can be arranged parallel or antiparallel, as shown here.