Ti-doped A-site deficient lanthanum manganites: Local structure and properties

Abstract

A study of La0.6Sr0.4-xMnTi xO3 (x=0.0, 0.05, 0.1, 0.15, and 0.2) manganites with the Ti in B(=Mn)-position and vacancies in A(=La, Sr)-site is presented. The manganites belonged to the rhombohedral phase and small amount of Mn 3O4 oxide was observed with increase of Ti content. X-ray adsorption fine structure (XAFS) analysis showed an appearance of Mn 2+ ions in perovskite cell and tremendous change of local structure. We suppose that the change of local structure was mainly caused by the appearance of Mn ions in the A-positions and partially by the formation of vacancies in the above position with the increase of x-value. Curie temperature, TC, decreased drastically with x: TC(x=0)=355K and, TC(x=0.05)=185K. Further increase of Ti content changed the low-temperature magnetic state from the ferromagnetic to spin/cluster glass state. Effects of destruction of the eg electron pathway and change of local structure on Curie temperature, caused by the Ti doping, is discussed. ?? 2005 Elsevier B.V. All rights reserved.