Coercive field and Grüneisen's law
Abstract
The general expression of the blocking temperature for a superparamagnetic system depends on the volume of the particle, but in this expression the volume is independent of temperature. Some experimental curves of the coercive field as a function of temperature show a minimum at relatively low temperatures. One way to obtain theoretical curves that qualitatively describe this behavior is by considering that these systems have two different regimes of thermal dilation when temperature increases: one for low temperatures and the other for high temperatures. In the present work it is shown how these theoretical curves of the coercive field can be calculated assuming these two different regimes and considering Grüneisen's law for low temperatures. Using the expression of the blocking temperature we have obtained the theoretical curve for the coercive field against temperature. In order to adjust the theoretical curve with the experimental one we have considered a volume model with respect to temperature taking into account Grüneisen's law for low temperatures.
- Publication:
-
Physica B Condensed Matter
- Pub Date:
- April 2019
- DOI:
- 10.1016/j.physb.2019.01.048
- Bibcode:
- 2019PhyB..559...29S
- Keywords:
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- Coercive field;
- Grüneisen's law;
- Blocking temperature