Swift heavy ion irradiation induced damage creation in nanocrystalline Li-Mg ferrite thin films

Nanocrystalline Li0.25Mg0.5Mn0.1Fe2.15O4 ferrite thin films, prepared by R.F. magnetron sputtering technique, are irradiated with 190 MeV Au14+ ions. The significant behavioural changes in magnetic and electrical properties of thin films after swift heavy ion irradiation confirm the formation of stable defects. A transformation from ferrimagnetic to superparamagnetic behaviour is observed from CEMS (conversion electron Mossbauer spectroscopy) with increase in fluence from 2.5 x 10(12) to 1 x 10(13) ions/cm(2). The resistivity initially increases after irradiation till the fluence reaches 1 x 10(12) ions/cm(2) and then reduces with further increase in fluence. We have also studied the X-ray diffraction pattern with fluence variation. A possible explanation of the above results on the basis of thermal spike model is presented. These effects are mainly due to amorphized latent tracks and variation in the cation distribution due to heavy ion irradiation. (C) 2004 Elsevier B.V. All rights reserved.