Electronic transport and 1/f noise studies in 250 MeV 107Ag ion irradiated La0.75Ca0.25MnO3 thin films

The influence of 250 MeV Ag-107 ion irradiation on electrical transport and low frequency conduction noise properties of La0.75Ca0.25MnO3 (LCMO) thin films have been investigated. A systematic variation of metal-insulator transition temperature T-p and resistivity as a function of ion fluence has been observed. It has been noted that for the sample irradiated with 10(11) ions/cm(2), T-p increased by 10 K and the resistivity is decreased in the ferromagnetic metallic state from that of an unirradiated sample, whereas our noise results show a monotonic increase in the normalized noise S-v/V-2, as a function of ion fluence. The observed modifications in the noise properties of the irradiated LCMO thin films are consistent with the general expectation concerning the effect of swift heavy ions irradiation induced lattice defects. (C) 1999 American Institute of Physics. [S0021-8979(99)08720-4].