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Title: Magnetic properties of Co{sub 2−x}TM{sub x}C and Co{sub 3−x}TM{sub x}C nanoparticles

Using synthetic chemical approaches, it is now possible to synthesize transition metal carbides nanoparticles with morphology, where the transition metal layers are embedded with intervening layers of carbon atoms. A composite material consisting of Co{sub 2}C and Co{sub 3}C nanoparticles has been found to exhibit unusually large coercivity and energy product. Here, we demonstrate that the magnetic moments and the anisotropy can be further enhanced by using a combination of Co and other transition metals (TM). Our studies are based on mixed nanoparticles Co{sub 2−x}TM{sub x}C and Co{sub 3−x}TM{sub x}C, in which selected Co sites are replaced with 3d transition elements Cr, Mn, and Fe. The studies indicate that the replacement of Co by Fe results in an increase of both the magnetic moment and the magnetic anisotropy. In particular, CoFe{sub 2}C is shown to have an average spin moment of 2.56 μ{sub B} and a magnetic anisotropy of 0.353 meV/formula unit compared to 1.67 μ{sub B} and 0.206 meV/formula unit for the Co{sub 3}C. Detailed examination of the electronic structure shows that the limited hybridization of carbon p-states with transition metal d-states drives the larger anisotropy.
Authors:
;  [1]
  1. Department of Physics, Virginia Commonwealth University, Richmond, Virginia 23284 (United States)
Publication Date:
OSTI Identifier:
22267788
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 114; Journal Issue: 24; Other Information: (c) 2013 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ANISOTROPY; CARBIDES; CARBON; CARBON DIOXIDE; CARBONATES; COERCIVE FORCE; COMPOSITE MATERIALS; D STATES; ELECTRONIC STRUCTURE; LAYERS; MAGNETIC MOMENTS; MAGNETIC PROPERTIES; NANOSTRUCTURES; P STATES; SPIN; TRANSITION ELEMENTS