The influence of electric current on the transport behaviour of La 0.7 Ce 0.3 MnO 3 thin epitaxial films on (001) LaAlO 3 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.

No abstract

We report the effect of electric current and magnetic field, separately and in conjugation, on the transport behaviour of patterned La0.7Ce0.3MnO3 thin films. In the absence of a magnetic field, a significant reduction in peak resistance (Rp) was found with increasing bias current. This effect is also present when a magnetic field is applied, though the magnitude of the electroresistance (ER = [R(I = 0.05 µA)−R(I = 50 µA)]/R(I = 50 µA)) decreases. The metal–insulator transition temperature (Tp) increases both with increasing current and with magnetic field. We observe an interesting correlation between electric current and magnetic field: the magnetoresistance (MR = [RH = 0−RH = 1 T]/RH = 0) decreases with increasing bias current, while ER decreases with increasing magnetic field. Both ER and MR show a maximum near Tp. The interesting correlation between these two effects suggests that both these effects arise from the same origin.