Current induced electroresistance in Nd0.5Ca0.5Mn0.95Ni0.05O3

We have investigated the dc and pulsed current induced electroresistance in phase separated manganite Nd0.5Ca0.5Mn0.95Ni0.05O3 (NCMONi05) as a function of temperature and magnetic field. It is shown that the negative differential resistance which appears above a threshold current (Ic) and hysteresis in the V-I progressively vanish with increasing period of the current pulses. However a strong nonlinearity in V-I exists even for a pulse period of 6 s. The peak voltage at Ic decreases in magnitude and shifts towards higher current values with increasing strength of the magnetic field. The strong nonlinear behavior and the negative differential resistance in the dc current sweep are accompanied by a rapid increase of the sample surface temperature and therefore primarily arise from the Joule heating in the sample. While the Joule heating assists electroresistance in the high dc current regime, the nonlinearity in the pulsed current sweep and the resistivity switching between a high and low value induced by controlling the width and period of pulses cannot be explained solely on the basis of Joule heating.