https://doi.org/10.1140/epjb/s10051-022-00459-x
Regular Article - Solid State and Materials
A phenomenological theory of itinerant weak ferromagnetism
Hokkaido University of Education—Asahikawa, Hokumon-cho 9, 070–8621, Asahikawa, Hokkaido, Japan
Received:
23
September
2022
Accepted:
22
November
2022
Published online:
20
January
2023
A phenomenological theory is explored for itinerant weak ferromagnetism. Free energy including the higher order terms of 
and 
is introduced and examined. This free energy is derived from the mean-field free energy expression with the use of the Bragg–Williams entropy. We apply the present theory to the typical itinerant weak ferromagnetic materials 
, 
, and others. To determine the model parameters, we use the experimental value of the magnetization under the large magnetic field or the extension of the Arrott plot with a functional form of hyperbola. This extended Arrott plot would explain various experimentally observed M–H curves at finite temperatures. Finally, we discuss the Sommerfeld coefficient in magnetic fields based on the present theory.
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© The Author(s), under exclusive licence to EDP Sciences, SIF and Springer-Verlag GmbH Germany, part of Springer Nature 2023. Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.
