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Proceedings Paper

Low-frequency conductance fluctuations in a shape memory alloy near the martensite transition
Author(s): Arindam Ghosh; Ayan Guha; Arup Kumar Raychaudhuri
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Paper Abstract

We have investigated the conductance fluctuation in a shape memory alloy (NiTi-Nitinol) near its martensite transition in order to study how the noise evolves near a phase transition that is driven by long range elastic interactions. The alloy has a martensite start and completion temperatures of 333 K and 325 K respectively and change of around 6%-8% in resistance at the transition. The conductance fluctuation (noise) measurements were carried out using a 5-probe ac technique in the temperature interval 200 K to 400 K in wire samples with typical thickness 5 μm and width of 120 μm. The samples were annealed at high temperature to remove any effect of previous temperature or strain cycle. We made the following observations: (1) There is a large change in the measured noise spectral power S(f) at the transition. (2) Away from transition temperature S(f) follows a 1/f-type behavior. This changes drastically near the transition, where large spectral density appears for f <1 Hz, and this strong dependence tends to saturate around 1 mHz. (3) Close to the transition, the probability density function (PDF) deviates from a Gaussian distribution, and shows a significant contribution from a power-law distribution. (4) When the transition is tuned by an applied constant stress (staying close to but below the transition temperature range), a similar strongly frequency-dependent low frequency S(f) appears, accompanied by a non-Gaussian PDF with a power-law statistics.

Paper Details

Date Published: 25 May 2004
PDF: 10 pages
Proc. SPIE 5469, Fluctuations and Noise in Materials, (25 May 2004); doi: 10.1117/12.546138
Show Author Affiliations
Arindam Ghosh, Indian Institute of Science (India)
Ayan Guha, Indian Institute of Science (India)
Arup Kumar Raychaudhuri, Indian Institute of Science (India)

Published in SPIE Proceedings Vol. 5469:
Fluctuations and Noise in Materials
Dragana Popovic; Michael B. Weissman; Zoltan A. Racz, Editor(s)

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