Magnetic properties of irradiated highly anisotropic materials

We have developed an ion irradiation technique that allows us to tune the magnetic properties of several magnetic alloys which are considered as promising candidates for ultra-high density magnetic recording such as FePd, FePt and CoPt/sub 3/ films. Depending both on the initial microstructure of the films and temperature used during irradiation, the chemical order and the resulting magnetic anisotropy can be either increased or decreased in a very controlled way. We discuss the possible mechanisms involved in ordering processes under irradiation.