Electroresistive effects in electron doped manganite La_0.7Ce_0.3MnO₃ thin films

Abstract

The influence of electric current on the transport behaviour of La_0.7Ce_0.3MnO₃ thin epitaxial films on (001) LaAlO₃ substrate is studied. Measurements were carried out in the regime of low current densities (0.0325–32.5 A cm^-2), for dc current in the absence of magnetic field. Significant reduction of the peak resistance (R_p) with monotonic increase in the metal–insulator transition temperature (T_p) was found with increasing bias current. The voltage current characteristics at various temperatures above and below T_p show nonlinearity for small currents. The behaviours of the resistance with the current are similar at various temperatures: an initial decrease with increasing current and then a levelling off. The magnetoresistance (MR) measurement under a field of 1 T revealed that it is maximum at the temperature near T_p at which the electroresistance (ER) is also maximum. The variation of resistance with electric field and magnetic field is non-hysteretic. We explain the origin of the observed ER and MR in our samples on the basis of double-exchange interaction and the phase separation phenomenon.