Fabricating high-density magnetic storage elements by low-dose ion beam irradiation

We fabricate magnetic storage elements by irradiating an antiferromagnetically coupled ferromagnetic/nonmagnetic/ferromagnetic trilayer by a low-dose ion beam. The irradiated areas become ferromagnetically coupled and are capable of storing information if their size is small enough. We employ Fe/Cr/Fe trilayers and a 30 keV focused Ga+-ion beam to demonstrate the working principle for a storage array with a bit density of 7 Gbit/in.2. Micromagnetic simulations suggest that bit densities of at least two magnitudes of order larger should be possible.