Coercive Fields Above 6 T in Two Cobalt(II)-Radical Chain Compounds

Xiaoqing Liu; Xiaowen Feng; Katie R Meihaus; Xixi Meng; Yuan Zhang; Liang Li; Jun-Liang Liu; Kasper S Pedersen; Lukas Keller; Wei Shi; Yi-Quan Zhang; Peng Cheng; Jeffrey R Long

doi:10.1002/anie.202002673

Coercive Fields Above 6 T in Two Cobalt(II)-Radical Chain Compounds

Angew Chem Int Ed Engl. 2020 Jun 22;59(26):10610-10618. doi: 10.1002/anie.202002673. Epub 2020 May 11.

Authors

Xiaoqing Liu¹, Xiaowen Feng², Katie R Meihaus², Xixi Meng¹, Yuan Zhang¹, Liang Li¹, Jun-Liang Liu³, Kasper S Pedersen⁴, Lukas Keller⁵, Wei Shi¹, Yi-Quan Zhang⁶, Peng Cheng¹, Jeffrey R Long^{2

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Affiliations

¹ Key Laboratory of Advanced Energy Materials Chemistry (MOE), Renewable Energy Conversion and Storage Center, College of Chemistry, Nankai University, Tianjin, 300071, China.
² Department of Chemistry, University of California, Berkeley, CA, 94720, USA.
³ Key Laboratory of Bioinorganic and Synthetic Chemistry of Ministry of Education, School of Chemistry, Sun Yat-Sen University, Guangzhou, 510275, China.
⁴ Department of Chemistry, Technical University of Denmark, DK-2800, Kgs. Lyngby, Denmark.
⁵ Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institute, CH-5232, Villigen PSI, Switzerland.
⁶ Jiangsu Key Laboratory for NSLSCS, School of Physical Science and Technology, Nanjing Normal University, Nanjing, 210023, China.
⁷ Department of Chemical and Biomolecular Engineering, University of California, Berkeley, CA, 94720, USA.
⁸ Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.

PMID: 32285987
DOI: 10.1002/anie.202002673

Abstract

Lanthanide permanent magnets are widely used in applications ranging from nanotechnology to industrial engineering. However, limited access to the rare earths and rising costs associated with their extraction are spurring interest in the development of lanthanide-free hard magnets. Zero- and one-dimensional magnetic materials are intriguing alternatives due to their low densities, structural and chemical versatility, and the typically mild, bottom-up nature of their synthesis. Here, we present two one-dimensional cobalt(II) systems Co(hfac)₂ (R-NapNIT) (R-NapNIT=2-(2'-(R-)naphthyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide, R=MeO or EtO) supported by air-stable nitronyl nitroxide radicals. These compounds are single-chain magnets and exhibit wide, square magnetic hysteresis below 14 K, with giant coercive fields up to 65 or 102 kOe measured using static or pulsed high magnetic fields, respectively. Magnetic, spectroscopic, and computational studies suggest that the record coercivities derive not from three-dimensional ordering but from the interaction of adjacent chains that compose alternating magnetic sublattices generated by crystallographic symmetry.

Keywords: coercive field; magnetic hysteresis; magnetism; molecular magnetism; single-chain magnets.

Abstract

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