Unusual current-induced electroresistance in epitaxial thin films ofLa0.8Ca0.2MnO3

Abstract

The transport behavior of ${\text{La}}_{0.8}{\text{Ca}}_{0.2}{\text{MnO}}_{3}$ thin films with Curie temperature ${T}_{\mathrm{C}}$ at $\ensuremath{\sim}286\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ has been investigated under various applied currents in the absence of magnetic field. An unusual current-induced electroresistance (ER) was observed. When the applied current density reaches a critical value, the films could not revert to the initial state. A novel state can be induced by a suitable large current, in which the insulation-metal transition temperature remains almost unchanged comparing with the initial state, whereas the value of the peak resistance is very sensitive to the applied current. Even a rather low current density can depress it significantly. ER reaches $\ensuremath{\sim}43%$ under a small current of $0.5\phantom{\rule{0.3em}{0ex}}\text{mA}$ (density $\ensuremath{\sim}1\ifmmode\times\else\texttimes\fi{}{10}^{4}\phantom{\rule{0.3em}{0ex}}\mathrm{A}\phantom{\rule{0.3em}{0ex}}{\text{cm}}^{\ensuremath{-}2}$). The observed ER effect seems to favor a percolative phase separation picture.