Grain-boundary effects on the magnetoresistance properties of perovskite manganite films

TLDR: The role of grain boundaries in the magnetoresistance (MR) properties of the manganites has been investigated and the polycrystalline films show large MR over a wide temperature range down to 5 K.

Abstract: The role of grain boundaries in the magnetoresistance (MR) properties of the manganites has been investigated by comparing the properties of epitaxial and polycrystalline films of ${\mathrm{La}}_{067}{D}_{033}\mathrm{Mn}{\mathrm{O}}_{3\ensuremath{-}\ensuremath{\delta}} (D=\mathrm{C}\mathrm{a},\phantom{\rule{0ex}{0ex}}\mathrm{S}\mathrm{r},\phantom{\rule{0ex}{0ex}}\mathrm{o}\mathrm{r}\phantom{\rule{0ex}{0ex}}\mathrm{v}\mathrm{a}\mathrm{c}\mathrm{a}\mathrm{n}\mathrm{c}\mathrm{i}\mathrm{e}\mathrm{s})$ While the MR in the epitaxial films is strongly peaked near the ferromagnetic transition temperature and is very small at low temperatures, the polycrystalline films show large MR over a wide temperature range down to 5 K The results are explained in terms of switching of magnetic domains in the grains and disorder-induced canting of Mn spins in the grain-boundary region