ANISOTROPY OF THE ATOMIC MOVEMENTS INDUCED IN AMORPHOUS METALLIC ALLOYS BY SWIFT HEAVY-ION IRRADIATION

Ion electronic energy loss induces both damage creation and anisotropi c dimensional changes in amorphous metallic alloys irradiated with swi ft heavy ions. These atomic rearrangements can be accounted for by a t wo-hit phenomenological model where the first hit initiates the damage production and the second hit leads to the sample growth. The key-iss ue was then to determine which of the two hits is responsible for the anisotropy of the atomic movements causing the growth. A hint was prov ided by an experiment in a particular geometry where the angle between the normal to the sample and the ion beam direction was varied severa l times during irradiation. The electrical resistance measurements dem onstrate that the anisotropy of the sample growth is entirely due to t he second event.