Direct correlation between 1/f magnetonoise and magnetoresistance in La_0.7Sr_0.3MnO₃ and (La_0.5Pr_0.2)Ba_0.3MnO₃ manganites

Abstract

Temperature- and magnetic-field-dependent electrical noise and electrical resistivity measurements were carried out on epitaxial thin films of a large bandwidth La_0.7Sr_0.3MnO₃ and a disordered intermediate bandwidth (La_0.5Pr_0.2)Ba_0.3MnO₃ manganite system. The power spectral density was dominated by 1/f noise. This 1/f noise was observed to follow the overall temperature dependence of the resistivity. Moreover, in these compounds the magnetonoise effect was found to be of nearly the same magnitude as the magnetoresistance. This direct correlation between magnetonoise and magnetoresistance suggests that the enhanced 1/f noise has its origin in intrinsic charge-carrier density fluctuations.