Al Ma'Mari, F orcid.org/0000-0002-6207-1168, Moorsom, T orcid.org/0000-0002-1771-7185, Teobaldi, G orcid.org/0000-0001-6068-6786 et al. (13 more authors) (2015) Beating the Stoner criterion using molecular interfaces. Nature, 524 (7563). pp. 69-73. ISSN 0028-0836
Abstract
Only three elements are ferromagnetic at room temperature: the transition metals iron, cobalt and nickel. The Stoner criterion explains why iron is ferromagnetic but manganese, for example, is not, even though both elements have an unfilled 3d shell and are adjacent in the periodic table: according to this criterion, the product of the density of states and the exchange integral must be greater than unity for spontaneous spin ordering to emerge. Here we demonstrate that it is possible to alter the electronic states of non-ferromagnetic materials, such as diamagnetic copper and paramagnetic manganese, to overcome the Stoner criterion and make them ferromagnetic at room temperature. This effect is achieved via interfaces between metallic thin films and C60 molecular layers. The emergent ferromagnetic state exists over several layers of the metal before being quenched at large sample thicknesses by the material's bulk properties. Although the induced magnetization is easily measurable by magnetometry, low-energy muon spin spectroscopy provides insight into its distribution by studying the depolarization process of low-energy muons implanted in the sample. This technique indicates localized spin-ordered states at, and close to, the metal-molecule interface. Density functional theory simulations suggest a mechanism based on magnetic hardening of the metal atoms, owing to electron transfer. This mechanism might allow for the exploitation of molecular coupling to design magnetic metamaterials using abundant, non-toxic components such as organic semiconductors. Charge transfer at molecular interfaces may thus be used to control spin polarization or magnetization, with consequences for the design of devices for electronic, power or computing applications (see, for example, refs 6 and 7).
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | (c) 2015 Macmillan Publishers Limited. All rights reserved. This is an author produced version of a paper published in Nature. Uploaded in accordance with the publisher's self-archiving policy |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Engineering & Physical Sciences (Leeds) > School of Physics and Astronomy (Leeds) > Condensed Matter (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 21 Aug 2015 12:53 |
Last Modified: | 12 Dec 2024 11:24 |
Published Version: | http://dx.doi.org/10.1038/nature14621 |
Status: | Published |
Publisher: | Nature Publishing Group |
Identification Number: | 10.1038/nature14621 |
Related URLs: | |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:89179 |