Anisotropy of the atomic movements induced in amorphous metallic alloys by swift heavy ion irradiation

Ion electronic energy loss induces both damage creation and anisotropic dimensional changes in amorphous metallic alloys irradiated with swift heavy ions. These atomic rearrangements can be accounted for by a two-hit phenomenological model where the first hit initiates the damage production and the second hit leads to the sample growth. The key-issue was then to determine which of the two hits is responsible for the anisotropy of the atomic movements causing the growth. A hint was provided by an experiment in a particular geometry where the angle between the normal to the sample and the ion beam direction was varied several times during irradiation. The electrical resistance measurements demonstrate that the anisotropy of the sample growth is entirely due to the second event.