Effects of Bi substitution on electroresistance behaviours in La0.8-xBixNa0.2MnO3 manganites

The observation of the electroresistance (ER) effect related to the reduction of resistivity under increased applied current indicates the potential of manganite material for next-generation spintronic-based devices. The observed behaviour was attributed to the presence of magnetic inhomogeneity. However, such relation is still not well understood, hence the current-induced effect on the resistivity in monovalent-doped La0.8-xBixNa0.2MnO3 (x = 0-0.20) manganite prepared via solid-state method is reported. All samples exhibited low resistivity in the temperature ranges of 30 K-300 K under a higher applied current of 5 mA compared with 1 mA, leading to the observation of the ER effect. The reduction of resistivity in the metallic region was due to the enhancement of DE itinerant hopping and the decrease in the scattering effect of conduction electrons, whereas in the insulating region, resistivity reduction is suggested to be related to the weakening of the electron-lattice attraction, as indicated by the reduction in activation energy (Ea) of charge carriers. Both x = 0.15 and x = 0.20 samples respectively exhibited large ER effects of 158% and 171% at 300 K amongst the studied samples. The enhancement of ER with Bi substitution is suggested due to the presence of magnetic inhomogeneities induced by MnO6 distortion which favours the formation of filamentary conduction paths under the presence of high applied current. The findings indicate that Bi substitution in La0.8-xBixNa0.2MnO3 (x = 0-0.20) manganites enhanced the sensitivity to the changes in electric field which shows that the investigated samples could be potentially used for non-volatile memory devices.