Colossal electroresistance in Sm0.55Sr0.45MnO3

We report a colossal resistance drop around insulator–metal transition temperature ( T MI ) in Sm 0.55 Sr 0.45 MnO 3 induced by direct current. Polycrystalline samples of Sm 0.55 Sr 0.45 MnO 3 were synthesized through solid state reaction method. They have been investigated by X-ray diffraction for phase evaluation, scanning electron microscopy for grain morphology and dc resistivity measurement techniques for resistivity–temperature behavior. The resistivity–temperature behavior has been measured with different biasing currents (1 mA, 2.5 mA, 5 mA, 10 mA and 50 mA). With increasing biasing current, the resistivity of the samples decreased drastically. The change in the resistivity of the samples for bias currents 1 mA and 50 mA at T MI was found to be ∼2560%. This phenomenon of electroresistance is discussed in view of strong interaction between carrier spins and localized spins in Mn ions and percolative mechanism of phase-separation.