Controllable colossal electroresistance inLa0.8Ca0.2MnO3epitaxial thin films

Abstract

We observed a significant enhancement of electric resistivity excited by a dc current in ${\mathrm{La}}_{0.8}{\mathrm{Ca}}_{0.2}{\mathrm{MnO}}_{3}$ epitaxial thin films. Such an enhanced resistance can be achieved when the applied dc current exceeds a threshold value. It also strongly depends on the duration of the dc current excitation. The induced enhancement in resistance can be well controlled by varying the duration of the current excitation. More attractive is that the enhanced resistance is extremely sensitive to weak currents. Even a very small dc current can remarkably depress the induced resistance, showing a colossal electroresistance (ER) in a very wide temperature range, even to room temperature. The maximum of ER can reach $\ensuremath{\sim}1350%$ for temperatures lower than $\ensuremath{\sim}50\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ and $\ensuremath{\sim}580%$ even at 300 K when the current changes from 0.7 to 10 $\ensuremath{\mu}\mathrm{A}$. Structure measurements on a microarea by the micrometer x-ray diffraction technique were carried out. No change of the structure and lattice parameter was found upon current treatments. Phase separation is taken into account in the interpretation of the observed phenomena.