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| Titel |
Measuring the Curie temperature |
| VerfasserIn |
K. Fabian, V. P. Shcherbakov, S. A. McEnroe |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250064911
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| Zusammenfassung |
| The measurement of Curie or Néel temperatures is one of the central techniques in rock
magnetism, because it is a relatively fast and reliable method to determine the predominant
magnetic minerals in natural samples, even if their concentrations are relatively small.
Unfortunately, the results of different commonly used measurement protocols for the same
sample can deviate enough to be confusing. Serious problems occur especially for studies
which interpret differences in Curie temperatures obtained from M(T)- and Ï(T)-
measurements, and many of these results must be questioned, or even disregarded.
Primarily this is due to insufficient theoretical foundation, leading to incompatible TC
values when determinations by different measurements are evaluated by the same or
similar methods. Using Landau theory for in-field magnetization measurements,
high-temperature measurement procedures are studied to revise the common evaluation
routines for M(T)- and Ï(T)-curves. While at least four different physical processes can
contribute to the low-field initial susceptibility near the ordering temperature, each of
which may influence the apparent position of TC, high-field methods are better
defined, but do not truly trace a second-order phase transition. Here, a series of
theoretical calculations are compared to high-temperature VSM measurements of
quarter-hysteresis loops, a procedure developed to efficiently measure several hysteresis
parameters in a single heating cycle. This method is equally as fast as a typical TC
determination on a Curie balance and provides a considerable amount of additional
information which can be modeled to obtain a more robust Curie Temperature. |
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