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A scanning tunneling microscopy and potentiometry study of epitaxial thin films of La0.7Ca0.3MnO3

Paranjape, Mandar and Shankar, Shantha K and Raychaudhuri, AK and Mathur, ND and Blamire, MG (2002) A scanning tunneling microscopy and potentiometry study of epitaxial thin films of La0.7Ca0.3MnO3. In: MRS Proceedings, 738 .

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Official URL: http://journals.cambridge.org/action/displayAbstra...

Abstract

To investigate the role of grain boundaries and other growth related microstructure in manganite films, a scanning tunneling microscope is used to simultaneously probe surface topography and local potential distribution under current flow at nanometer level in films of epitaxial thin films of La0.7Ca0.3MnO3 deposited on single crystal SrTiO3 and NdGaO3 substrate by laser ablation. We have studied two types of films strained and strain relaxed. Thin (50nm) films (strained due to lattice mismatch between substrate and the film) show step growth (unit cell steps) and have very smooth surfaces. Relatively thicker films (strain relaxed, thickness 200nm) do not have these step growths and show rather smooth well connected grains. Charge transport in these films is not uniform on the nanometer level and is accompanied by potential jumps at the internal surfaces. In particular scattering from grain boundaries results in large variations in the local potential resulting in fields as high as 104-105V/cm located near the grain boundaries. We discuss the role of local strain and strain inhomogeneties in determining the current transport in these films and their resistance and magnetoresistivity. In this paper we attempt to correlate between bulk electronic properties with microscopic electronic conduction using scanning tunneling microscopy and scanning tunneling potentiometry.

Item Type: Journal Article
Additional Information: Copyright of this article belongs to Cambridge University Press.
Department/Centre: Division of Physical & Mathematical Sciences > Physics
Date Deposited: 17 Aug 2011 08:30
Last Modified: 17 Aug 2011 08:30
URI: http://eprints.iisc.ernet.in/id/eprint/39918

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