π-anisotropy: a nanocarbon route to hard magnetism

Moorsom, T. et al. (2020) π-anisotropy: a nanocarbon route to hard magnetism. Physical Review B, 101(6), 060408(R). (doi: 10.1103/PhysRevB.101.060408)

Abstract

High coercivity magnets are an important resource for renewable energy, electric vehicles, and memory technologies. Most hard magnetic materials incorporate rare earths such as neodymium and samarium, but concerns about the environmental impact and supply stability of these materials are prompting research into alternatives. Here, we present a hybrid bilayer of cobalt and the nanocarbon molecule C 60 which exhibits significantly enhanced coercivity with minimal reduction in magnetization. We demonstrate how this anisotropy enhancing effect cannot be described by existing models of molecule-metal magnetic interfaces. We outline a form of anisotropy, arising from asymmetric magnetoelectric coupling in the metal-molecule interface. Because this phenomenon arises from π − d hybrid orbitals, we propose calling this effect π -anisotropy. While the critical temperature of this effect is currently limited by the rotational degree of freedom of the chosen molecule, C 60 , we describe how surface functionalization would allow for the design of room-temperature, carbon-based hard magnetic films.

• Item Type: Articles
• Additional Information: This work was funded by EPSRC (Grants No. EP/I004483, No. EP/K036408, No. EPSRC EP/S030263/1, and No. EP/S031081/1), EPSRC Programme grant on Skyrmionics (Grant No. EP/N032128/1), The Horizon 2020 European Research Infrastructure project OpenDreamKit (676541), and a Taibah University Ph.D. Scholarship. This work made use of the ARCHER (via the UKCP Consortium, EPSRC UK EP/P022189/1 and EP/P022189/2), UK Materials and Molecular Modelling Hub (EPSRC UK EP/P020194/1), and STFC Scientific Computing Department’s SCARF High-Performance Computing facilities.
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Moorsom, Dr Timothy
• Authors: Moorsom, T., Alghamdi, S., Stansill, S., Poli, E., Teobaldi, G., Beg, M., Fangohr, H., Rogers, M., Aslam, Z., Ali, M., Hickey, B.J., and Cespedes, O.
• College/School: College of Science and Engineering > School of Physics and Astronomy
• Journal Name: Physical Review B
• Publisher: American Physical Society
• ISSN: 2469-9950
• ISSN (Online): 2469-9969
• Published Online: 28 February 2020
• Copyright Holders: Copyright © 2020 American Physical Society
• First Published: First published in Physical Review B 101(6): 060408(R)
• Publisher Policy: Reproduced in accordance with the publisher copyright policy