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Unveiling the Hidden Entropy in ZnFe(2)O(4)

The antiferromagnetic (AFM) transition of the normal ZnFe(2)O(4) has been intensively investigated with results showing a lack of long-range order, spin frustrations, and a “hidden” entropy in the calorimetric properties for inversion degrees δ ≈ 0 or δ = 0. As δ drastically impacts the magnetic pro...

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Autores principales: Cobos, Miguel Angel, Hernando, Antonio, Marco, José Francisco, Puente-Orench, Inés, Jiménez, José Antonio, Llorente, Irene, García-Escorial, Asunción, de la Presa, Patricia
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2022
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8840487/
https://www.ncbi.nlm.nih.gov/pubmed/35161142
http://dx.doi.org/10.3390/ma15031198
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author Cobos, Miguel Angel
Hernando, Antonio
Marco, José Francisco
Puente-Orench, Inés
Jiménez, José Antonio
Llorente, Irene
García-Escorial, Asunción
de la Presa, Patricia
author_facet Cobos, Miguel Angel
Hernando, Antonio
Marco, José Francisco
Puente-Orench, Inés
Jiménez, José Antonio
Llorente, Irene
García-Escorial, Asunción
de la Presa, Patricia
author_sort Cobos, Miguel Angel
collection PubMed
description The antiferromagnetic (AFM) transition of the normal ZnFe(2)O(4) has been intensively investigated with results showing a lack of long-range order, spin frustrations, and a “hidden” entropy in the calorimetric properties for inversion degrees δ ≈ 0 or δ = 0. As δ drastically impacts the magnetic properties, it is logical to question how a δ value slightly different from zero can affect the magnetic properties. In this work, (Zn(1-δ)Fe(δ))[Zn(δ)Fe(2-δ)]O(4) with δ = 0.05 and δ = 0.27 have been investigated with calorimetry at different applied fields. It is shown that a δ value as small as 0.05 may affect 40% of the unit cells, which become locally ferrimagnetic (FiM) and coexists with AFM and spin disordered regions. The spin disorder disappears under an applied field of 1 T. Mossbauer spectroscopy confirms the presence of a volume fraction with a low hyperfine field that can be ascribed to these spin disordered regions. The volume fractions of the three magnetic phases estimated from entropy and hyperfine measurements are roughly coincident and correspond to approximately 1/3 for each of them. The “hidden” entropy is the zero point entropy different from 0. Consequently, the so-called “hidden” entropy can be ascribed to the frustrations of the spins at the interphase between the AFM-FiM phases due to having δ ≈ 0 instead of ideal δ = 0.
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spelling pubmed-88404872022-02-13 Unveiling the Hidden Entropy in ZnFe(2)O(4) Cobos, Miguel Angel Hernando, Antonio Marco, José Francisco Puente-Orench, Inés Jiménez, José Antonio Llorente, Irene García-Escorial, Asunción de la Presa, Patricia Materials (Basel) Article The antiferromagnetic (AFM) transition of the normal ZnFe(2)O(4) has been intensively investigated with results showing a lack of long-range order, spin frustrations, and a “hidden” entropy in the calorimetric properties for inversion degrees δ ≈ 0 or δ = 0. As δ drastically impacts the magnetic properties, it is logical to question how a δ value slightly different from zero can affect the magnetic properties. In this work, (Zn(1-δ)Fe(δ))[Zn(δ)Fe(2-δ)]O(4) with δ = 0.05 and δ = 0.27 have been investigated with calorimetry at different applied fields. It is shown that a δ value as small as 0.05 may affect 40% of the unit cells, which become locally ferrimagnetic (FiM) and coexists with AFM and spin disordered regions. The spin disorder disappears under an applied field of 1 T. Mossbauer spectroscopy confirms the presence of a volume fraction with a low hyperfine field that can be ascribed to these spin disordered regions. The volume fractions of the three magnetic phases estimated from entropy and hyperfine measurements are roughly coincident and correspond to approximately 1/3 for each of them. The “hidden” entropy is the zero point entropy different from 0. Consequently, the so-called “hidden” entropy can be ascribed to the frustrations of the spins at the interphase between the AFM-FiM phases due to having δ ≈ 0 instead of ideal δ = 0. MDPI 2022-02-04 /pmc/articles/PMC8840487/ /pubmed/35161142 http://dx.doi.org/10.3390/ma15031198 Text en © 2022 by the authors. https://creativecommons.org/licenses/by/4.0/Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).
spellingShingle Article
Cobos, Miguel Angel
Hernando, Antonio
Marco, José Francisco
Puente-Orench, Inés
Jiménez, José Antonio
Llorente, Irene
García-Escorial, Asunción
de la Presa, Patricia
Unveiling the Hidden Entropy in ZnFe(2)O(4)
title Unveiling the Hidden Entropy in ZnFe(2)O(4)
title_full Unveiling the Hidden Entropy in ZnFe(2)O(4)
title_fullStr Unveiling the Hidden Entropy in ZnFe(2)O(4)
title_full_unstemmed Unveiling the Hidden Entropy in ZnFe(2)O(4)
title_short Unveiling the Hidden Entropy in ZnFe(2)O(4)
title_sort unveiling the hidden entropy in znfe(2)o(4)
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8840487/
https://www.ncbi.nlm.nih.gov/pubmed/35161142
http://dx.doi.org/10.3390/ma15031198
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