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Effect of the Internal Pressure Due to the A-Site Cations on the Giant Magnetoresistance and Related Properties of Doped Rare Earth Manganates, $Ln_{1-x}A_xMnO_3$ (Ln = La, Nd, Gd, Y; A = Ca, Sr, Ba, Pb)

Mahesh, R and Mahendiran, R and Raychaudhuri, AK and Rao, CNR (1995) Effect of the Internal Pressure Due to the A-Site Cations on the Giant Magnetoresistance and Related Properties of Doped Rare Earth Manganates, $Ln_{1-x}A_xMnO_3$ (Ln = La, Nd, Gd, Y; A = Ca, Sr, Ba, Pb). In: Journal of Solid State Chemistry, 120 (1). pp. 204-207.

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Abstract

Based on an extensive study of a large variety of rare earth manganates (rare earth = La, Nd, Gd, or Y) with Ca, Sr, Ba, and Pb as the substituents, as well as of $LaMnO_3$ samples with varying $Mn^{4+}$ content, it is shown that the ferromagnetic transition temperature, $T_{c'}$ as well as the insulator-metal (I-M) transition temperature, $T_{r'}$ increases with the weighted average radius of the A-cations, $\langle r_\lambda\rangle$, showing a maximum at 1.23 ± 0.01 A. The essentially linear region $(\langle r_\lambda\rangle$ = 1.18-1.24 A) demarcates the ferromagnetic metal and paramagnetic insulator regimes. The peak resistivity at the I-M transition, as well as the magnitude of the magnetoresistance (MR), decreases with increasing $\langle r_\lambda\rangle$. Only below a $\langle r_\lambda\rangle$ of 1.23 ± 0.01 A is the MR greater than 50%.

Item Type: Journal Article
Additional Information: The copyright belongs to Academic pess.
Department/Centre: Division of Chemical Sciences > Solid State & Structural Chemistry Unit
Division of Physical & Mathematical Sciences > Physics
Date Deposited: 20 Nov 2006
Last Modified: 19 Sep 2010 04:29
URI: http://eprints.iisc.ernet.in/id/eprint/7664

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