Swift ion irradiation induced changes in the structural and transport properties of La0.7Sr0.3MnO3 thin films

Highly c-axis oriented, magnetoresistive thin films of La0.7Sr0.3MnO3 deposited on LaAlO3(1 0 0) (LAO) substrates by pulsed laser deposition have been subjected to thermal annealing and subsequently to irradiation with swift heavy ions. While the as-deposited films show insulator metal transition Tp at ∼265 K, the annealed films show metallic behavior over a wide temperature range viz. from 125 K to 400 K. We have investigated the effect of 90 MeV O7+ ions and 200 MeV Ag15+ ions on structural and electrical properties of these films. Dose values ranging from 1 × 1012 to 1 × 1014 ions/cm2 of O7+ ions and from 1 × 1011 to 1 × 1012 ions/cm2 of Ag15+ ions were used. The metal–insulator transition reoccurs in the irradiated films and the Tp can be tailored to room temperature with irradiation dose value and energy of the ion. Attempt is made to comprehend this variation in Tp on the basis of swift ion irradiation induced defects and related strain rather than change in oxygen content of the films.