查看文章

We report the low temperature (below the metal–insulator transition temperature T_im) resistivity and magnetoresistance (MR) behavior of 50 MeV Li³⁺ beam irradiated La_0.7Pb_0.3MnO₃ for three different fluences. Ion beam irradiation causes a decrease of T_im leading to the increase of insulating regime. Resistivity data of the unirradiated as well as irradiated samples fitted well with an equation of the form ρ=ρ₀+ρ_2.5T^2.5 which indicates predominant contribution from the electron–magnon interaction (second term). The temperature dependent MR data of samples irradiated with different ion fluences follow the simple relation [MR=a+b/(T+C)] showing appreciable effect of radiation on the parameters a, b and C. The physical significance of the radiation effect on these parameters is not yet very clear.