https://doi.org/10.1140/epjp/s13360-025-06353-6
Regular Article
Investigation of the paramagnetic state and itinerant electron magnetism in YCo12−xFexB6 (x = 0–4) intermetallic compounds
1
CNRS, Institut Néel, Université Grenoble Alpes, BP166X, 38042, Grenoble Cedex 9, France
2
European Synchrotron Radiation Facility, 38042, Grenoble Cédex 9, France
3
CNRS, IJL, Université de Lorraine, 54000, Nancy, France
a
valletsimond.baptiste@gmail.com
Received:
19
December
2024
Accepted:
22
April
2025
Published online:
21
May
2025
This work aims to investigate the delocalization degree of itinerant electrons in the YCo12−xFexB6 compounds through Takahashi’s theory of spin fluctuations. The paramagnetic state of the YCo12−xFexB6 series of compounds is first studied through the evolution of the Curie and Curie–Weiss temperatures as a function of the Fe content. The parent compound YCo12B6 is a ferromagnet with TC = 155(3) K, 
= 144(3) K and 0.45(4) µB/3d at. at 2 K, while the Fe-rich compound YCo8Fe4B6 shows the behaviour of a very weakly ferromagnetic compound with TC = 51(5) K, = − 41(5) K and 0.11(4) µB/3d at. at 2 K, markers of dominant antiferromagnetic (AFM) interactions. The paramagnetic state was also studied through the evolution of the effective paramagnetic moment compared to the measured moment in the magnetically ordered state. We then applied Takahashi’s theory of spin fluctuations to macroscopic magnetization data to determine the physical parameters TA and T0, usually accessible only through local probe methods. The YCo12−xFexB6 series of compounds was placed on the Deguchi-Takahashi plot, from a slightly delocalized state (peff/ps = 4.27 for x = 0) towards a fully delocalized state (peff/ps = 23.54 for x = 4) by increasing the Fe content. Other markers, like the Curie–Weiss temperature, the metamagnetic transitions for x = 1.5 to 2.5, and the shape parameter s of the thermal evolution of the spontaneous magnetization indicate that this delocalization of the itinerant electron magnetism is accompanied by a progressive strengthening of the AFM interactions as Fe content increases. This study shows that magnetic properties of the YCo12−xFexB6 family of compounds can only be explained properly by accounting for the spin fluctuations, as they help to transcribe the evolution from a rather localized itinerant electron magnetism towards a completely delocalized case.
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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.
