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Mapping of local electronic properties in nanostructured CMR thin films by Scanning Tunneling Microscopy (STM) and Local Conductance Map (LCMAP)

Published online by Cambridge University Press:  01 February 2011

Sohini Kar ,
Barnali Ghosh ,
L. K. Brar ,
M A. Paranjape  and
A. K. Raychaudhuri
Sohini Kar
Affiliation:
Department of Physics Indian Institute of Science, Bangalore 560 012, India
Barnali Ghosh
Affiliation:
Department of Physics Indian Institute of Science, Bangalore 560 012, India
L. K. Brar
Affiliation:
Department of Physics Indian Institute of Science, Bangalore 560 012, India
M A. Paranjape
Affiliation:
Department of Physics Indian Institute of Science, Bangalore 560 012, India
A. K. Raychaudhuri
Affiliation:
Department of Physics Indian Institute of Science, Bangalore 560 012, India
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Abstract

We have investigated the local electronic properties and the spatially resolved magnetoresistance of a nanostructured film of a colossal magnetoresistive (CMR) material by local conductance mapping (LCMAP) using a variable temperature Scanning Tunneling Microscope (STM) operating in a magnetic field. The nanostructured thin films (thickness ≈500nm) of the CMR material La0.67Sr0.33MnO3 (LSMO) on quartz substrates were prepared using chemical solution deposition (CSD) process. The CSD grown films were imaged by both STM and atomic force microscopy (AFM). Due to the presence of a large number of grain boundaries (GB's), these films show low field magnetoresistance (LFMR) which increases at lower temperatures.

The measurement of spatially resolved electronic properties reveal the extent of variation of the density of states (DOS) at and close to the Fermi level (EF) across the grain boundaries and its role in the electrical resistance of the GB. Measurement of the local conductance maps (LCMAP) as a function of magnetic field as well as temperature reveals that the LFMR occurs at the GB. While it was known that LFMR in CMR films originates from the GB, this is the first investigation that maps the local electronic properties at a GB in a magnetic field and traces the origin of LFMR at the GB.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 838: Symposium O – Scanning Probe and Other Novel Microscopies of Local Phenomena in Nanostructured Materials , 2004 , O10.13
Copyright
Copyright © Materials Research Society 2005

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References

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