Magnetic properties and ferromagnetic microstructures in Al-doped La 1-xSrxMnO3

Abstract

Doping effect on ferromagnetic (FM) properties in perovskite manganites La1-xSrxMnO3 (x=0.175) were investigated by low-temperature Lorentz transmission electron microscopy (TEM), in combination with the conventional magnetic measurements. It is found that La 0.825Sr0.175Mn0.95Al0.05O 3 exhibits a structural phase transition from the rhombohedral to orthorhombic structures at Ts∼116 K. During the rhombohedral-to-orthorhombic transition, the FM domain structures changed from the macroscopic FM domains to the FM ones with the wavy stripe pattern. The ac magnetic measurements also revealed that La0.825Sr0.175Mn0.95Al 0.05O3 shows unconventional magnetic behaviour at low temperature below 65 K. Partial substitution of non-magnetic Al3+ for Mn3+ has some influence on magnetic ordering and double-exchange interaction, which should induce insulator behaviour in the orthorhombic phase. © 2010 IOP Publishing Ltd.