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Title: Magnetic properties of Co2-xTMxC and Co3-xTMxC 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 Co2C and Co3C nanoparticies 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 Co2-x TMxC and Co3-xTMxC, 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, CoFe2C is shown to have an average spin moment of 2.56 mu(B) and a magnetic anisotropy of 0.353 meV/formula unit compared to 1.67 mu(B) and 0.206 meV/formula unit for the Co3C. Detailed examination of the electronic structure shows that the limited hybridization of carbon p-states with transition metal d-states drives the larger anisotropy. (C) 2013 AIP Publishing LLC.
Publication Date:
OSTI Identifier:
DOE Contract Number:
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 114; Journal Issue: 24
Sponsoring Org:
USDOE Advanced Research Projects Agency - Energy (ARPA-E)
Country of Publication:
United States