Measurements of magnetoresistance and magnetization were carried out on ceramic samples of La_{0.5}Pb_{0.5}MnO_{3} and La_{0.5}Pb_{0.5}MnO_{3}, containing 10 at. % Ag in a dispersed form. The results obtained for the resistivity at zero applied magnetic field exhibit a shallow minimum at temperatures T about 25 K - 30 K, which shifts towards lower temperatures upon applying magnetic field and disappears at a certain (rather low) field. Also the resistivity at helium temperature decreases upon applying magnetic fields. It is shown that the model of spin-dependent carrier tunneling between antiferromagnetically coupled grains may account for the results observed.
@article{arxiv.cond-mat/0007363,
title = {A nature of low-temperature resistivity minimum in ceramic manganites},
author = {E. Rozenberg and M. Auslender and I. Felner and G. Gorodetsky},
journal= {arXiv preprint arXiv:cond-mat/0007363},
year = {2013}
}