The influence of static-electric field on the transport properties in La0.7Ca0.3MnO3 epitaxial thin films

We investigated the effect of static-electric field on the transport properties in La0.7Ca0.3MnO3 (LCMO) epitaxial thin films using a field effect configuration (FEC). A single layer LCMO film with thickness about 100 nm was grown on LaAlO3 (LAO) substrate by pulsed laser deposition technique. A simple FEC was then formed on it using lithography technique, in which the LCMO film was used as channel, and LAO substrate as gate. Such a simple configuration is much easier to fabricate compared to the previously reported multilayer FEC. The transport behaviors of the LCMO channel for electric field bias ranging from +80 to -80 V were studied. Field effect is found to be significant. The maximum of electroresistance (ER) reaches 32%. An important feature is that the ER changes sign with the field direction, but the temperature T-P, at which the resistance peaks, keeps nearly unchanged upon any bias. The films could return to their pristine state completely after the bias was removed, and the ER effect can be fully reproducible. However, we found a critical bias exists for these films. When the applied bias reaches +170 V, the system could not revert to its initial state, instead a high resistive peak appears at low temperature. The appeared resistive peak behaves sensitively to small currents. A weak current could remarkably depress the resistance. The observed phenomena are discussed in the framework of phase separation mechanism. (C) 2006 American Institute of Physics.