Current driven discontinuous insulator-metal transition and colossal low-field magnetoresistance in Sm0.6Sr0.4MnO3

It is shown that with increasing magnitude of current (I), resistivity of Sm0.6Sr0.4MnO3 transforms from a smooth to a discontinuous insulator-metal transition which is also accompanied by an abrupt decrease in temperature of the sample. We report colossal low-field magnetoresistance under a high current bias (-99% at H = 0.5 T and 70 K) and electroresistance (-8000 % at H = 0 T and 60 K) for I = 11 mA. We interpret our observations in terms of current induced supercooling of the high temperature paramagnetic phase and enlargement of volume fraction of the ferromagnetic phase under a magnetic field.