90 MeV 16O ion irradiation effects on transport and magnetization in epitaxial thin films of La0.75Ca0.25MnO3

The influence of 90 MeV O-16 ion irradiation on the electric and magnetic properties of epitaxial thin films of La0.75Ca0.25MnO3 is studied. These films were deposited on LaAlO3(100) substrates by the pulsed excimer laser deposition technique. The thickness of each film was about 3000 Angstrom. The high quality of the films was ensured by x-ray diffraction and transport measurements. The films were irradiated with 90 MeV oxygen ions at different doses (10(11)-10(14) ions/cm(2)). It is observed that at a low dose of 10(11) ions/cm(2) the resistivity peak temperature (T-p) and the Curie temperature (T-c) increase, however as the dose is increased further, the T-p and T-c decrease. At the higher dose of 10(14) ions/cm(2), the film becomes insulating and does not show any peak in the resistivity-temperature curve down to 60 K. These results are discussed in terms of the effects of ion induced compositional inhomogeneity and strain on the film properties. (C) 1998 American Institute of Physics.