Magneticproperties of $La_{0.5-x}Ln_xSr_{0.5}MnO_3$ (Ln=Pr, Nd, Gd and Y)

Seikh, Motin Md and Sudheendra, L and Rao, CNR (2004) Magneticproperties of $La_{0.5-x}Ln_xSr_{0.5}MnO_3$ (Ln=Pr, Nd, Gd and Y). In: Journal of Solid State Chemistry, 177 (10). pp. 3633-3639.

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Abstract

Magnetic and electron transport properties of four series of manganates of the composition $La_{0.5-x}Ln_xSr_{0.5}MnO_3$ (Ln=Pr, Nd, Gd and Y) have been investigated to examine how the ferromagnetic metallic nature of the parent La compound changes over to antiferromagneticinsulating behavior, with change in Ln and x due to the associated changes in the A-site cation radius as well as the size disorder. When Ln=Pr and Nd, there is a transition from the tetragonal I4/mcm structure to the orthorhombic Immm and Imma structures at x = 0.2 and 0.35, respectively. There is a gradual evolution of the properties from those of $La_{0.5}Sr_{0.5}MnO_3$ to those of $Pr_{0.5}Sr_{0.5}MnO_3$ or $Nd_{0.5}Sr_{0.5}MnO_3$ with increase in x. Thus, when x>0.2 and >0.35 respectively, the Pr- and Nd-substituted manganates show ferromagnetic transitions followed by antiferromagnetictransitions at low temperatures, with the ferromagnetic $T_C$ decreasing with increasing x. The Gd and Y series of compounds are all orthorhombic and show a decrease in $T_C$ with the increase in x, the ferromagnetism disappearing at high x. At a value of x corresponding to the A-site cation radius of $Pr_{0.5}Sr_{0.5}MnO_3$ the Gd and Y series of compounds exhibit ferromagnetism in the 250­-300K region and undergo an antiferromagnetictransition on cooling. The $T_C-T_N$ gap is sensitive to the disorder arising from the size mismatch.

Item Type:	Journal Article
Publication:	Journal of Solid State Chemistry
Publisher:	Elsevier Inc
Additional Information:	The copyright of this article belongs to Elsevier Inc.
Keywords:	Manganates, rare earth;Ferromagnetism, in rare earth manganates;Jahn­Teller distortion;Size-disorder,in rare earth manganates
Department/Centre:	Division of Chemical Sciences > Solid State & Structural Chemistry Unit
Date Deposited:	27 Nov 2007
Last Modified:	19 Sep 2010 04:25
URI:	http://eprints.iisc.ac.in/id/eprint/6142

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