Curie-Weiss law
The Curie-Weiss law (according to Pierre Curie and Pierre-Ernest Weiss ) describes the magnetic properties of ferromagnetic substances in which magnetic cooperative effects lead to a deviation from the ideal Curie behavior . Such cooperative effects occur due to the exchange interaction, the direct interaction of magnetic dipole moments of neighboring paramagnetic atoms plays a subordinate role. This influence leads to ferromagnetism below the Curie temperature .
The Curie-Weiss law shows the temperature dependence of the magnetic susceptibility of a ferromagnet in the high temperature phase, i.e. H. above the Curie temperature
with the Curie constant .
The equation states that the magnetic susceptibility in the paraphase diverges as the temperature approaches the Curie temperature from above .
Analogue for ferromagnetic and antiferromagnetic systems
In ferromagnetic and antiferromagnetic systems, the magnetic susceptibility above their phase transition temperature , the Néel temperature , can be described by a slightly modified formula:
In this case, the susceptibility of the high-temperature phase apparently “diverges” towards a negative temperature.
literature
- Heiko Lueken : Magnetochemistry . BG Teubner, Stuttgart / Leipzig 1999, ISBN 3-519-03530-8 .
- Bergmann-Schaefer Textbook of Experimental Physics Volume 2: Electricity and Magnetism 7th edition, de Gruyter, 1987, ISBN 3-11-010261-7
Individual evidence
- ^ Entry on Curie-Weiss law. In: Römpp Online . Georg Thieme Verlag, accessed on July 24, 2016.