Magnetic properties of irradiated highly anisotropic materials

We have developed an ion irradiation technique that allows us to tune the m agnetic properties of several magnetic alloys which are considered as promi sing candidates for ultra-high density magnetic recording such as FePd, FeP t and CoPt3 films. Depending both on the initial microstructure of the film s and temperature used during irradiation the chemical order and the result ing magnetic anisotropy can be either increased or decreased in a very cont rolled way. We discuss the possible mechanisms involved in ordering process es under irradiation.