Influence of Al-doping on the structural, magnetic, and electrical properties of La$_{1-x}$Ba$_x$Mn$_{1-x}$Al$_x$O$_3$ ($0\leq x \leq 0.25$) manganites

TL;DR

This study investigates how aluminum doping affects the structural, magnetic, and electrical properties of La$_{1-x}$Ba$_x$Mn$_{1-x}$Al$_x$O$_3$ manganites, revealing decreased transition temperatures and phase changes with increased Al content.

Contribution

It provides new insights into the effects of Al doping on manganite properties, including phase structure, magnetic behavior, and electrical conduction mechanisms.

Findings

Unit cell volume decreases with Al doping.

T$_c$ decreases as Al substitutes Mn.

Samples exhibit Griffiths and spin-glass magnetic phases.

Abstract

We have studied the effect of Al doping on the structural, magnetic and electrical properties of La$_{1-x}$Ba$_x$Mn$_{1-x}$Al$_x$O$_3$ ($0\leq x \leq 0.25$) manganite, annealed in two 750$^oC$ and 1350$^oC$ temperatures. The XRD analysis shows that the structures in all samples have single phase rhombohedral structure with R$\bar{3}$c space group. The unit cell volume almost decrease with increasing the Al doping in all samples. The grain growth with increasing annealing temperature and Al doping also have been studied. We observed that, T$_c$ temperature decreases when the Al ion substitute in Mn ion site. The magnetic study of the samples via magnetic susceptibility results in Griffiths and spin-glass phase for samples doped with aluminium. Along the resistivity measurement results, the $T_{MIT}$ (metal-insulator) transition temperatures decrease and the system become an insulator. The insulator-metal transition occurs for L0 sample in near 165K, while this transition is weak for H0 sample due to oxygen non-stoichiometry.Using three models viz. 1. Adiabatic small polaron hoping, 2.Variable range hopping, and 3. Percolation model, the resistance have been studied.