Monovalent effects on structural, magnetic and magnetoresistance properties in doped manganite oxides

Structural, magnetic and magneto-transport properties of La 0.7Sr0.3-xNaxMnO3 (0≤x≤0.2) manganites have been investigated. Our samples, elaborated by the classical ceramic method, crystallized in the rhombohedrally distorted perovskite structure with R3̄c space group. Magnetic measurements showed that our compounds exhibit a paramagnetic-ferromagnetic transition with decreasing temperature. The Curie temperature decreases with increasing Na content. Electrical investigations showed that all our samples exhibit a semi-conducting behavior at high temperature and a metallic-like one at low temperature. A large magnetoresistance of 29% has been observed at room temperature and in 5T in the bulk of La0.7Sr0.1Na0.2MnO3 compound. © 2003 Elsevier B.V. All rights reserved.