Electrical transport and magnetoresistance properties of (1 − x)La0.6Sr0.4MnO3/x(Sb2O3) composites

• Ferromagnetism is suppressed due to the magnetic dilution by Sb2O3 addition.
• Transport behavior is governed by the percolation model.
• Enhanced MR due to the suppression of enhanced spin-dependent scattering with field.

Magneto-transport and magnetic studies on the (1 − x)(La0.6Sr0.4MnO3)/xSb2O3 (x = 0.00, 0.03, 0.07, 0.12 and 0.18) composite system are reported. X-ray and microanalysis results reveal that there is no evidence of reaction between the La0.6Sr0.4MnO3 and Sb2O3 grains. The Curie temperature TC of the composite system remains unchanged; however, magnetization decreases with Sb2O3 addition. Metal–insulator transition temperatures (Tρ) are found to lie in the range of 298–324 K for the derived samples at zero applied magnetic field. The increase of resistivity (ρ) is related to the influence of the grain boundaries on the electrical conduction process. The percolation theory is introduced to understand and improve the properties of these mixed systems. An enhanced magnetoresistance (MR) at the whole temperature range and under a low magnetic field is observed in the composites with x = 0.03. We argue that the MR improvement is ascribed to the enhanced magnetic disorder at interfaces and grain boundaries as well as to the suppression of enhanced spin-dependent scattering of the conduction electrons by the applied magnetic field.

Temperature dependence of resistivity for (La0.6Sr0.4MnO3)1 − x/(Sb2O3)x composites measured at 0 T and 5 T applied field. The solid lines are the resistivity calculated using the following expression:ρ(T)=f×(ρ0+ρ2T2)+(1-f)×ραexpEaKBTFigure optionsDownload as PowerPoint slide