The effect of MgO doping on the structural, magnetic, and magnetotransport properties of La0.8Sr0.2MnO3 manganite

The effect of MgO doping on the structural, magnetic, and magnetotransport properties of La0.8Sr0.2MnO3 (LSMO)/xMgO has been investigated. All samples were prepared by a solid-state reaction method. Alternating current susceptibility measurements for LSMO/xMgO samples show that the Curie transition temperature (Tc) and magnetization decrease with the increase of MgO concentration. The rate of the decrease of Tc at higher doping level is very fast. Also, samples with low doping level (x ≤ 2) show insulator-metal transition, but the transition temperature decreases and resistivity increases with the amount of MgO. It is observed that there is no insulator-metal transition at higher MgO doping level (x ≥ 3). Also, the results show that the value of low-field magnetoresistance decreases with the increase of MgO doping level. It seems that due to the higher sintering temperature and almost the same ionic radii of Mg2+ and Mn3+, Mg2+ mostly replaced Mn3+ and weakened the double-exchange interaction, and consequently, Tc and magnetoresistance decrease and resistivity increases with MgO doping.