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Breaking through the Mermin-Wagner limit in 2D van der Waals magnets

The Mermin-Wagner theorem states that long-range magnetic order does not exist in one- (1D) or two-dimensional (2D) isotropic magnets with short-ranged interactions. Here we show that in finite-size 2D van der Waals magnets typically found in lab setups (within millimetres), short-range interactions...

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Autores principales: Jenkins, Sarah, Rózsa, Levente, Atxitia, Unai, Evans, Richard F. L., Novoselov, Kostya S., Santos, Elton J. G.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Nature Publishing Group UK 2022
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9663506/
https://www.ncbi.nlm.nih.gov/pubmed/36376290
http://dx.doi.org/10.1038/s41467-022-34389-0
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author Jenkins, Sarah
Rózsa, Levente
Atxitia, Unai
Evans, Richard F. L.
Novoselov, Kostya S.
Santos, Elton J. G.
author_facet Jenkins, Sarah
Rózsa, Levente
Atxitia, Unai
Evans, Richard F. L.
Novoselov, Kostya S.
Santos, Elton J. G.
author_sort Jenkins, Sarah
collection PubMed
description The Mermin-Wagner theorem states that long-range magnetic order does not exist in one- (1D) or two-dimensional (2D) isotropic magnets with short-ranged interactions. Here we show that in finite-size 2D van der Waals magnets typically found in lab setups (within millimetres), short-range interactions can be large enough to allow the stabilisation of magnetic order at finite temperatures without any magnetic anisotropy. We demonstrate that magnetic ordering can be created in 2D flakes independent of the lattice symmetry due to the intrinsic nature of the spin exchange interactions and finite-size effects. Surprisingly we find that the crossover temperature, where the intrinsic magnetisation changes from superparamagnetic to a completely disordered paramagnetic regime, is weakly dependent on the system length, requiring giant sizes (e.g., of the order of the observable universe ~ 10(26) m) to observe the vanishing of the magnetic order as expected from the Mermin-Wagner theorem. Our findings indicate exchange interactions as the main ingredient for 2D magnetism.
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spelling pubmed-96635062022-11-15 Breaking through the Mermin-Wagner limit in 2D van der Waals magnets Jenkins, Sarah Rózsa, Levente Atxitia, Unai Evans, Richard F. L. Novoselov, Kostya S. Santos, Elton J. G. Nat Commun Article The Mermin-Wagner theorem states that long-range magnetic order does not exist in one- (1D) or two-dimensional (2D) isotropic magnets with short-ranged interactions. Here we show that in finite-size 2D van der Waals magnets typically found in lab setups (within millimetres), short-range interactions can be large enough to allow the stabilisation of magnetic order at finite temperatures without any magnetic anisotropy. We demonstrate that magnetic ordering can be created in 2D flakes independent of the lattice symmetry due to the intrinsic nature of the spin exchange interactions and finite-size effects. Surprisingly we find that the crossover temperature, where the intrinsic magnetisation changes from superparamagnetic to a completely disordered paramagnetic regime, is weakly dependent on the system length, requiring giant sizes (e.g., of the order of the observable universe ~ 10(26) m) to observe the vanishing of the magnetic order as expected from the Mermin-Wagner theorem. Our findings indicate exchange interactions as the main ingredient for 2D magnetism. Nature Publishing Group UK 2022-11-14 /pmc/articles/PMC9663506/ /pubmed/36376290 http://dx.doi.org/10.1038/s41467-022-34389-0 Text en © The Author(s) 2022 https://creativecommons.org/licenses/by/4.0/Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/ (https://creativecommons.org/licenses/by/4.0/) .
spellingShingle Article
Jenkins, Sarah
Rózsa, Levente
Atxitia, Unai
Evans, Richard F. L.
Novoselov, Kostya S.
Santos, Elton J. G.
Breaking through the Mermin-Wagner limit in 2D van der Waals magnets
title Breaking through the Mermin-Wagner limit in 2D van der Waals magnets
title_full Breaking through the Mermin-Wagner limit in 2D van der Waals magnets
title_fullStr Breaking through the Mermin-Wagner limit in 2D van der Waals magnets
title_full_unstemmed Breaking through the Mermin-Wagner limit in 2D van der Waals magnets
title_short Breaking through the Mermin-Wagner limit in 2D van der Waals magnets
title_sort breaking through the mermin-wagner limit in 2d van der waals magnets
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9663506/
https://www.ncbi.nlm.nih.gov/pubmed/36376290
http://dx.doi.org/10.1038/s41467-022-34389-0
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