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Coupling of Small Lattice Polarons to Magnetic Field in Magnetoresistive Manganites

Meneghini, C and Castellano, C and Kumar, Ashwani and Ray, Sugata and Sarma, DD and Mobilio, S (1999) Coupling of Small Lattice Polarons to Magnetic Field in Magnetoresistive Manganites. In: physica status solidi, 215 . pp. 647-652.

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Abstract

We report Extended X-Ray Absorption Fine Structure measurements at the Mn K absorption edge on hole doped manganese oxides ${La}_{1-x}Ca_x{MnO}_3$ in a wide temperature range above and below the metal insulator transition temperature in presence of a magnetic field. In accordance with previous studies an anomalous increase in the Debye Waller factors is detected at the phase transition in the first coordination shell made up of O atoms. This is due to a local structural deformation around $Mn^{3+}$ atoms associated with the Jahn-Teller effect and the formation of polarons. The application of a magnetic field results in a variation of this deformation with a thermal behaviour that closely resembles that of the magnetoresistance. This confirms the relevance of the polarons on the conductivity properties of such materials. The magnetic field has a huge effect on the second coordination shell probably related with the change of the Mn-O-Mn angle upon application of the magnetic field.

Item Type: Journal Article
Additional Information: The copyright belongs to WILEY-VCH Verlag Berlin GmbH.
Keywords: doped manganese oxides;insulator transition temperature;x ray absorption
Department/Centre: Division of Chemical Sciences > Solid State & Structural Chemistry Unit
Date Deposited: 06 Oct 2005
Last Modified: 19 Sep 2010 04:20
URI: http://eprints.iisc.ernet.in/id/eprint/3804

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