Effect of substituting Ru4+ and other tetravalent ions in the B-site of rare earth manganates on the magneto-transport properties and charge-ordering

✍ Scribed by P.V. Vanitha; Anthony Arulraj; A.R. Raju; C.N.R. Rao

• Publisher: Elsevier Science
• Year: 1999
• Tongue: English
• Weight: 607 KB
• Volume: 2
• Category: Article
• ISSN: 1387-1609
• DOI: 10.1016/s1387-1609(00)88571-0

✦ Synopsis

Substitution of Ti and Zr in the B-site of La,,7Ca0,3Mn03 lowers the Tc and the temperature of insulator-metal transition. Substitution of Ru in the B-site of La0,7Ca0,3Mn03, however, does not alter the T, or TIM significantly. More importantly, the effect of substitution of Ti and Zr in the B-site of the charge-ordered Nd0,5Ca,,5Mn03 progressively destroys the charge-ordering in this insulating material. In contrast, substitution by Ru in the B-site renders the material ferromagnetic with the T, increasing with the Ru content and the material also shows insulator-metal transition. This marked effect of Ru substitution on the charge-ordering is also seen in Nd,,,5Sr,,5Mn03 where the T, increases with Ru content while charge-ordering gets destroyed. The extraordinary effect of Ru in favouring the ferromagnetic metallic state and destroying the charge-ordering is attributed mainly to its unique electronic configuration (48:). 0 1999 A ca d emie des sciences I gditions scientifiques et medicales Elsevier SAS. rare earth manganates I colossal magnetoresistivity I charge ordering / ruthenium in manganates