Synergistic effects of La and Mn vacancies on the structural and magnetoelectric transport properties of LaMn1+xO3+δ manganites

Regulation of magnetoelectric properties through defect engineering in perovskite manganites has attracted increasing attention in recent years. However, the mechanisms by which La and Mn vacancies influence the structural and magnetoelectric properties of these manganites remain insufficiently understood and require further investigation. In this study, we systematically explored the effects of Mn stoichiometry on the oxygen content, La and Mn vacancy concentrations, as well as the structural and magnetoelectric transport properties of LaMn_1+xO_3+δ manganites. As x increases, both the oxygen content and La vacancy concentration increase, while the Mn vacancy concentration decreases. The variation in unit cell volume is mainly attributed to changes in the Mn⁴⁺ content, which are influenced by the total cation vacancy concentrations. Additionally, ferromagnetism is significantly enhanced with increasing x. When x ≤ 0.02, the ceramics exhibit semiconducting behavior, whereas an apparent metal–insulator transition occurs at higher x values. Notably, Mn vacancies are found to play a dominant role in determining the magnetoelectric transport properties of LaMn_1+xO_3+δ ceramics. Moreover, the maximum magnetoresistance (MR) of LaMn_1+xO_3+δ ceramics reaches 30.8% at 120.4 K for x = 0.03, while a significantly enhanced MR is observed at 253.1 K with a value of 47.8% for LaMn_1.05O_3+δ thin films. These findings provide critical insights into the synergistic effects of La and Mn vacancies on the magnetoelectric properties of perovskite manganites and highlight their promising potential for applications in magnetic and spintronic devices.