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Random Telegraph-like Signals in Ultrathin CMR Films

Published online by Cambridge University Press:  21 March 2011

A. Lisauskas ,
S. I. Khartsev  and
A. M. Grishin
A. Lisauskas
Affiliation:
Department of Condensed Matter Physics, Royal Institute of Technology, S-100 44 Stockholm, SWEDEN
S. I. Khartsev
Affiliation:
Department of Condensed Matter Physics, Royal Institute of Technology, S-100 44 Stockholm, SWEDEN
A. M. Grishin
Affiliation:
Department of Condensed Matter Physics, Royal Institute of Technology, S-100 44 Stockholm, SWEDEN
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Abstract

The aim of the present paper is to study low frequency (10 Hz - 10 kHz) noise in low dimensional colossal magnetoresistors (epitaxial CMR films). Two contributions in electrical fluctuations were observed: thermal noise, which depends on resistance and temperature, and excess part, which is determined by resistance fluctuations and are mostly related to film microstructure. For films, thicker than the critical thickness, excess noise spectra has 1/fα dependence with α = 1 ± 0.2. In films thinner than the critical one there are random telegraph like signals (TLS) with Lorentzian spectra appear on the background of 1/f noise. Noise spectroscopy reveals the relaxation process in 4.2 nm thick film has thermally activated character with an energy gap of 20 meV at temperatures below 156 K and 78 meV at T > 156 K.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 666: Symposium F – Transport and Microstructural Phenomena , 2001 , F7.11
Copyright
Copyright © Materials Research Society 2001

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References

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