I-V Characteristics of Resistive Oxides: DC versus Pulsed Measurements

We investigated pulsed and DC I-V characteristics of a variety of resistive oxides. Examples of pulsed, compared with DC characteristics, are shown for samples of La$\text{}_{1.2}$Sr$\text{}_{1.8}$Mn$\text{}_{2}$O$\text{}_{7}$ (a double layer manganite), Pr$\text{}_{2}\text{}_{/}\text{}_{3}$ Ca$\text{}_{1}\text{}_{/}\text{}_{3}$ MnO$\text{}_{3}$ and Bi$\text{}_{1}\text{}_{/}\text{}_{2}$ Sr$\text{}_{1}\text{}_{/}\text{}_{2}$ MnO$\text{}_{3}$ (charge-ordered manganites), Sr$\text{}_{2}$FeMoO$\text{}_{6}$, Sr$\text{}_{2}$CrWO$\text{}_{6}$ and Ba$\text{}_{2}$MnReO$\text{}_{6}$ (double perovskites). For pulsed measurements, single pulses in the ms range were applied. For short-rise-time square pulses, the Joule heating is negligible, as long as the response remains independent of time. The DC I-V characteristics were measured up to current runaway in the negative resistance regime;Δ T never exceeded a fraction of a degree. In most cases the DC characteristics mask a perfectly ohmic or moderately non-ohmic conductivity obtained by pulsed measurements. This demonstrates that the widely used DC I-V measurements in the high current regime are frequently misleading.