Colossal electroresistance and low-field colossal magnetoresistance in the single-crystal bilayered manganiteLa1.2Sr1.8Mn2O7

Abstract

We report the observation of current-induced abrupt transition from a metallic to an insulating state in a bilayered manganite ${\mathrm{La}}_{1.2}{\mathrm{Sr}}_{1.8}{\mathrm{Mn}}_{2}{\mathrm{O}}_{7}$ single crystal. A colossal electroresistance effect $[\ensuremath{\rho}(50\phantom{\rule{0.3em}{0ex}}\mathrm{mA})\ensuremath{-}\ensuremath{\rho}(1\phantom{\rule{0.3em}{0ex}}\mathrm{mA})]∕\ensuremath{\rho}(50\phantom{\rule{0.3em}{0ex}}\mathrm{mA})=93%$ is found at $120\phantom{\rule{0.3em}{0ex}}\mathrm{K}$. Moreover, the current-induced transition is very sensitive to external magnetic fields. At the measuring current of $50\phantom{\rule{0.3em}{0ex}}\mathrm{mA}$ a low-field colossal magnetoresistance effect, $[\ensuremath{\rho}(H)\ensuremath{-}\ensuremath{\rho}(0)]∕\ensuremath{\rho}(0)=\ensuremath{-}86%$, occurs at $H=500\phantom{\rule{0.3em}{0ex}}\mathrm{Oe}$. This low-field magnetoresistance effect can be repeatedly modulated by external magnetic field. We interpret these phenomena as the consequence of the percolative conduction and local Joule thermal effect.