Current localization and Joule self-heating effects in Cr doped Nd0.5Ca0.5MnO3 manganites

The effects of dc excitation current on the current-voltage curves of polycrystalline samples of Nd0.5Ca0.5Mn0.96Cr0.04O3 were investigated. The experimental results show that an abrupt jump of the voltage is concomitant with a huge increase in the temperature of the sample. A simple model and estimates for Joule self-heating effects support the experimental data. Moreover, the data strongly suggest that both the current localization in the metallic paths and local Joule self-heating effects are essential ingredients to understand the current-induced phase transition in phase-separated manganites.