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Direct observation of paramagnetic spin fluctuations in LaFe₁₃₋ₓ Siₓ

Faske, Tom ; Radulov, Iliya Angelov ; Hölzel, Markus ; Gutfleisch, Oliver ; Donner, Wolfgang (2021):
Direct observation of paramagnetic spin fluctuations in LaFe₁₃₋ₓ Siₓ. (Publisher's Version)
In: Journal of Physics: Condensed Matter, 32 (11), IOP Publishing, ISSN 0953-8984, e-ISSN 1361-648X,
DOI: 10.26083/tuprints-00019331,
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Item Type: Article
Origin: Secondary publication via sponsored Golden Open Access
Status: Publisher's Version
Title: Direct observation of paramagnetic spin fluctuations in LaFe₁₃₋ₓ Siₓ
Language: English
Abstract:

Spin fluctuations are a crucial driving force for magnetic phase transitions, but their presence usually is indirectly deduced from macroscopic variables like volume, magnetization or electrical resistivity. Here we report on the direct observation of spin fluctuations in the paramagnetic regime of the magnetocaloric model system LaFe₁₁.₆Si₁.₄ in the form of neutron diffuse scattering. To confirm the magnetic origin of the diffuse scattering, we correlate the temperature dependence of the diffuse intensity with ac magnetic susceptibility and x-ray diffraction experiments under magnetic field. Strong spin fluctuations are already observable at 295K and their presence alters the thermal contraction behavior of LaFe₁₁.₆Si₁.₄ down to the Curie temperature of the first-order magneto-structural transition at 190K. We explain the influence of the spin fluctuation amplitude on the lattice parameter in the framework of the internal magnetic pressure model and find that the critical forced magnetostriction follows Takashi’s spin fluctuation theory for itinerant electron systems.

Journal or Publication Title: Journal of Physics: Condensed Matter
Journal volume: 32
Number: 11
Publisher: IOP Publishing
Collation: 10 Seiten
Classification DDC: 600 Technik, Medizin, angewandte Wissenschaften > 600 Technik
Divisions: 11 Department of Materials and Earth Sciences > Material Science > Functional Materials
Date Deposited: 06 Sep 2021 12:13
Last Modified: 06 Sep 2021 12:14
DOI: 10.26083/tuprints-00019331
Corresponding Links:
URN: urn:nbn:de:tuda-tuprints-193310
URI: https://tuprints.ulb.tu-darmstadt.de/id/eprint/19331
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