A nano-carbon route to rare earth free permanent magnetism

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 the concerns about the environmental impact and supply stability of these materials is prompting research into alternatives. Here, we present a hybrid bilayer of cobalt and the nano-carbon molecule C60 which exhibits significantly enhanced coercivity with minimal reduction in magnetisation. We demonstrate how this anisotropy enhancing effect cannot be described by existing models of molecule-metal magnetic interfaces. We outline a new form of magnetic anisotropy, arising from asymmetric magneto-electric coupling in the metal-molecule interface. Because this phenomenon arises from pi-d hybrid orbitals, we propose calling this effect pi-anisotropy. While the critical temperature of this effect is currently limited by the rotational degree of freedom of the chosen molecule, C60, we describe how surface functionalisation would allow for the design of room-temperature, carbon based hard magnetic films.

16 pages, 4 figures

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• Resistivity due to a Domain Wall in Ferromagnetic Metal
• Controlling the Local Spin-Polarization at the Organic-Ferromagnetic Interface
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Cited by in corpus (7)

• Enhanced spin-orbit coupling in a heavy metal via molecular coupling
• A theoretical perspective on the modification of the magnetocrystalline anisotropy at molecule-cobalt interfaces
• Magnetoresistance and spintronic anisotropy induced by spin excitations along molecular spin chains
• Dynamical Screening of Local Spin Moments at Metal-Molecule Interfaces
• Low-energy, ultrafast spin reorientation at competing hybrid interfaces with tunable operating temperature
• Evidence of Spin-Glass state in Molecular Exchange-Bias System
• The dynamics of a driven harmonic oscillator coupled to pairwise interacting Ising spins in random fields