Colossal electroresistance and low-field colossal magnetoresistance in the single-crystal bilayered manganite La_(1.2)Sr_(1.8)Mn_2O_7

摘要

We report the observation of current-induced abrupt transition from a metallic to an insulating state in a bilayered manganite La_(1.2)Sr_(1.8)Mn_2O_7 single crystal. A colossal electroresistance effect [ρ(50 mA) -ρ(1 mA)]/ρ(50 mA)=93% is found at 120 K. Moreover, the current-induced transition is very sensitive to external magnetic fields. At the measuring current of 50 mA a low-field colossal magnetoresistance effect, [ρ(H)-ρ(0)]/ρ(0)=-86%, occurs at H=500 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.