Annealing effect on transport properties of Nd0.67Sr0.33MnO3 thin films

Pattabiraman, Mahesh and Murugaraj, P and Rangarajan, G and Prasad, V and Subramanyam, SV and Sastry, VS and Koo, Sang-Mo and Rao, K V (2000) Annealing effect on transport properties of Nd0.67Sr0.33MnO3 thin films. In: Pramana - Journal of Physics, 55 (3). pp. 455-469.

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Abstract

Annealing dependence of the lattice parameter, resistivity, magnetoresistance and thermopower have been studied on Nd0.87Sr0.33MnO3 thin films deposited on LaAlO3 and alumina substrates by pulsed laser ablation. Upon annealing at 800 degrees C and 1000 degrees C the lattice constant of the LaAlO3 film tends toward that of the bulk target due to reduction in oxygen vacancies. This results in a metal-insulator transition at temperatures which increase with progressive annealing along with a decrease in the observed low temperature MR. Using a magnon scattering model we estimate the e(g) bandwidth of the film annealed at 1000 degrees C and show that the magnon contribution to the resistivity is suppressed in a highly oxygen deficient film and gains prominence only upon subsequent annealing. We also show that upon annealing, the polaron concentration and the spin cluster size increases in the paramagnetic phase, using an adiabatic polaron hopping model which takes into account an exchange dependent activation energy above the resistivity peak.

Item Type:	Journal Article
Publication:	Pramana - Journal of Physics
Publisher:	Indian Academy of Sciences
Additional Information:	Copyright of this article belongs to Indian Academy of Sciences.
Keywords:	Colossal magnetoresistance -polaron -metal-insulator transition -thermopower -oxygen deficiency -manganite.
Department/Centre:	Division of Physical & Mathematical Sciences > Physics
Date Deposited:	30 Sep 2010 09:18
Last Modified:	30 Sep 2010 09:18
URI:	http://eprints.iisc.ac.in/id/eprint/32552

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