Low-temperature transport anomaly in the magnetoresistive compound (La_0.5Pr_0.2)Ba_0.3MnO₃

Abstract

Electronic and magnetoresistive properties of (La_0.5Pr_0.2)Ba_0.3MnO₃ (ABO₃ type) compound, having a large size-disorder at the A-site, have been studied in both polycrystalline bulk as well as in epitaxial thin-film forms. Both these forms of the sample display a resistivity minimum at a temperature (T_min) of ~45K; T_min shifts to higher temperatures on application of magnetic fields. Considering various possibilities, such as a grain boundary effect, Kondo scattering, and electron-electron (e-e) scattering for the cause of this resistivity minimum, we conclude that the minimum occurs due to e-e scattering caused by enhanced Coulombic interactions. A large size-disorder ~0.016 Ų in this compound is the major source of metallic disorder, resulting in the enhancement of Coulombic interactions.