Effect of La-doping on magnetic properties of Bi0.6−xLaxCa0.4MnO3 (0.0⩽x⩽0.6) perovskite manganites

Abstract

In this paper, we report the synthesis of polycrystalline samples with nominal compositions Bi0.6−xLaxCa0.4MnO3 (0.0⩽x⩽0.6) via the solid state reaction route and our study of their structural, magnetic and electrical transport properties with the variation of doping concentration of La. Magnetic measurements of the parent Bi0.6Ca0.4MnO3 compound reveal the presence of the robust charge-ordered antiferrromagnetic (COAFM) phase with charge-ordering temperature (TCO) ∼289 K and antiferromagnetic Néel temperature (TN) ∼136 K. The COAFM phase disappears when this compound is doped with La. Furthermore, the samples with x=0.2–0.6 exhibit paramagnetic-to-ferromagnetic (PM–FM) transition and PM–FM transition temperature (TC) decreases progressively from 270 to 203 K as x increases from 0.2 to 0.5. However, the samples with x=0.0 and 0.1 do not show PM–FM transition. The temperature-dependent resistance measurements of samples with x=0.0–0.4 exhibit an insulating behaviour, whereas samples with x=0.5 and 0.6 exhibit metal–insulator transition at ∼163 and 198 K, respectively. The experimental results are discussed on the basis of the character of the Bi3+ lone pair electron and the average A-site cation radius (⟨rA⟩).