Direct Correlation between 1/f-magneto-noise and magnetoresistance in La0.7Sr0.3MnO3 and (La0.5Pr0.2)Ba0.3MnO3 manganites

Temperature- and magnetic field-dependent electrical noise and electrical resistivity measurements were carried out on epitaxial thin films of a large bandwidth La0.7Sr0.3MnO3 and a disordered intermediate bandwidth (La0.5Pr0.2)Ba0.3MnO3 manganite system. The power spectraldensity 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 magneto-noise effect was found to be of nearly the same magnitude as the magnetoresistance. This direct correlation between magneto-noise and magnetoresistance suggests that the enhanced 1/f-noise has its origin in intrinsic charge-carrier density fluctuations.