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 $[\rho \left(50\mathrm{mA}\right)-\rho \left(1\mathrm{mA}\right)]∕\rho \left(50\mathrm{mA}\right)=93\%$ is found at $120\mathrm{K}$. Moreover, the current-induced transition is very sensitive to external magnetic fields. At the measuring current of $50\mathrm{mA}$ a low-field colossal magnetoresistance effect, $[\rho \left(H\right)-\rho \left(0\right)]∕\rho \left(0\right)=-86\%$, occurs at $H=500\mathrm{Oe}$. 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.

• Received 1 September 2005

DOI:https://doi.org/10.1103/PhysRevB.73.092404