Experimental critical exponents of 'pure' ferromagnets: The cost of excessive proximity to TC may be too high

The limited purity of available ferromagnetic materials may turn into a pitfall in experimental studies of critical phenomena. In pursuit of asymptotic critical behaviour it is not uncommon to approach the Curie point too closely, violating the condition |epsilon| > > DeltaT/TC, epsilon = (T -...

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Bibliographic Details
Published in:Europhysics letters 2006-02, Vol.73 (3), p.396-400
Main Authors: Kuz'min, M D, Tishin, A M
Format: Article
Language:English
Online Access:Get full text
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Summary:The limited purity of available ferromagnetic materials may turn into a pitfall in experimental studies of critical phenomena. In pursuit of asymptotic critical behaviour it is not uncommon to approach the Curie point too closely, violating the condition |epsilon| > > DeltaT/TC, epsilon = (T - TC)/TC (here DeltaT ~ DeltaxX103 K is the width of the critical region, Deltax being the fractional impurity content). If this happens, the presence of what is normally regarded as a tiny amount of impurity can no longer be neglected. One of the consequences is that the critical exponent beta is noticeably over-estimated in comparison with its value in the pure material (which is the quantity sought in such studies). This problem does not occur if the excessive proximity to the Curie point is avoided.
ISSN:0295-5075
DOI:10.1209/epl/i2005-10409-3