THERMAL SPIKE MODEL APPLIED TO THE IRRADIATED YTTRIUM-IRON-GARNET - MEAN DIFFUSION LENGTH OF THE ENERGY DEPOSITED ON THE ELECTRONS

Single crystals of yttrium iron garnet Y3Fe5O12 have been irradiated w ith 270 MeV Te-52, 760 MeV Kr-86 and 1040 MeV Pb-208 ions, The extent of the induced damage is determined using Rutherford backscattering sp ectrometry (RES) in channeling geometry with a 2 MeV He-4 beam. Taking into account these new results and the previous ones, the thermal spi ke model was applied to calculate track radii versus electronic stoppi ng power for different beam energies using only one fitting parameter, lambda the mean diffusion length of the energy deposited on the elect rons by the slowing down of a swift heavy ion in the garnet. As the la tent heat of fusion is unknown for yttrium garnet, the calculation was first performed by neglecting it, A lambda value of (6.3 +/- 0.3) nm is extracted by fitting all the different results taking into account a velocity effect. Such a lambda value is the high limit of the mean d iffusion length since it decreases if the latent heat of fusion is not neglected, This value of lambda is in agreement with the previous det erminations made in the same conditions for resistant insulators, show ing that lambda should decrease when the band-gap energy increases.