Current-sensitive electroresistance and the response to a magnetic field in La0.8Ca0.2MnO3 epitaxial thin films

Abstract

The influence of a transport dc current on the resistivity of La0.8Ca0.2MnO3 epitaxial thin films and their response to a magnetic field has been investigated. We found that when the applied dc current exceeds a threshold value, the electric resistivity in these films could be significantly enhanced. Such observations are completely repeatable. More attractive is that the enhanced resistance turns out to be sensitive to a weak current in a wide temperature range from 10 to 300 K. Even a very small dc current could remarkably depress the high resistance, showing a colossal electroresistance (ER) effect. ER reaches ~1175% at temperatures lower than ~50 K, and ~705% at 300 K for a current changing from 0.72 to 10.5 µA. A highly nonlinear behavior of the I–V curves persists even to room temperature. Significant influence of the magnetic field on the electric transports was also observed. It is found that a low field of 0.25 T could remarkably affect the I–V curves, resulting in a considerable magnetoresistance (MR). ©2005 American Institute of Physics.