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Toward On-and-Off Magnetism: Reversible Electrochemistry to Control Magnetic Phase Transitions in Spinel Ferrites

Dasgupta, Subho and Das, Bijoy and Li, Qiang and Wang, Di and Baby, Tessy T. and Indris, Sylvio and Knapp, Michael and Ehrenberg, Helmut and Fink, Karin and Kruk, Robert and Hahn, Horst (2016):
Toward On-and-Off Magnetism: Reversible Electrochemistry to Control Magnetic Phase Transitions in Spinel Ferrites.
26, In: Advanced Functional Materials, (41), Wiley-VCH Verlag GmbH, Weinheim, pp. 7507-7515, ISSN 1616301X, [Online-Edition: https://doi.org/10.1002/adfm.201603411],
[Article]

Abstract

The magnetoelectric effect, i.e., electric-field control of magnetism in artificial heterostructures is usually limited to surface/interface atoms of the magnetic materials. In order to attain electrical control of magnetism in bulk ferromagnets, this study proposes to extend the definition of magnetoelectric phenomena to include reversible, chemistry-controlled magnetization switching. A large and reversible change in the room temperature magnetization in strong ferromagnets is reported, with electrochemistry-driven Li-ion exchange; carefully chosen spinel ferrites demonstrate a reversible magnetization variation up to 50% for CuFe2O4 and 70% for ZnFe2O4. In case of CuFe2O4, the magnetization variation is predominantly associated with the preferential reduction of Cu2+ to Cu+ ions, and, hence, abides a nearly one-to-one relationship with the amount of injected Li-ions. In addition, the reduction of Cu2+ also annihilates the Fe3+-O-Cu2+ magnetic interaction, resulting in a marked decrease in the Neel temperature of CuFe2O4. In contrast, the electrical tuning of superexchange interactions is found to play the decisive role in ZnFe2O4, where the simple electrochemical reduction model of magnetic cations can only explain a nominal fraction of the total magnetization variation, and indeed an electrochemically controlled reversible change in transition temperature is found necessary to account for the large magnetization variation observed.

Item Type: Article
Erschienen: 2016
Creators: Dasgupta, Subho and Das, Bijoy and Li, Qiang and Wang, Di and Baby, Tessy T. and Indris, Sylvio and Knapp, Michael and Ehrenberg, Helmut and Fink, Karin and Kruk, Robert and Hahn, Horst
Title: Toward On-and-Off Magnetism: Reversible Electrochemistry to Control Magnetic Phase Transitions in Spinel Ferrites
Language: English
Abstract:

The magnetoelectric effect, i.e., electric-field control of magnetism in artificial heterostructures is usually limited to surface/interface atoms of the magnetic materials. In order to attain electrical control of magnetism in bulk ferromagnets, this study proposes to extend the definition of magnetoelectric phenomena to include reversible, chemistry-controlled magnetization switching. A large and reversible change in the room temperature magnetization in strong ferromagnets is reported, with electrochemistry-driven Li-ion exchange; carefully chosen spinel ferrites demonstrate a reversible magnetization variation up to 50% for CuFe2O4 and 70% for ZnFe2O4. In case of CuFe2O4, the magnetization variation is predominantly associated with the preferential reduction of Cu2+ to Cu+ ions, and, hence, abides a nearly one-to-one relationship with the amount of injected Li-ions. In addition, the reduction of Cu2+ also annihilates the Fe3+-O-Cu2+ magnetic interaction, resulting in a marked decrease in the Neel temperature of CuFe2O4. In contrast, the electrical tuning of superexchange interactions is found to play the decisive role in ZnFe2O4, where the simple electrochemical reduction model of magnetic cations can only explain a nominal fraction of the total magnetization variation, and indeed an electrochemically controlled reversible change in transition temperature is found necessary to account for the large magnetization variation observed.

Journal or Publication Title: Advanced Functional Materials
Volume: 26
Number: 41
Publisher: Wiley-VCH Verlag GmbH, Weinheim
Divisions: 11 Department of Materials and Earth Sciences > Material Science > Joint Research Laboratory Nanomaterials
11 Department of Materials and Earth Sciences > Material Science
11 Department of Materials and Earth Sciences
Date Deposited: 27 Jul 2017 08:06
Official URL: https://doi.org/10.1002/adfm.201603411
Identification Number: doi:10.1002/adfm.201603411
Funders: S.D. and H.H. would like to thank the financial support from the DFG grants DA 1781/1-1 and HA 1344/34-1, respectively., The DFT calculations have been performed on the JUSTUS HPC facility at the University of Ulm supported by the bwHPC initiative and the bwHPC-C5 project funded by the MWK and the German Research Foundation (DFG)., Q.L. was supported by the Helmholtz Research School "Energy-related catalysis".
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