Size-induced chemical and magnetic ordering in individual Fe-Au nanoparticles

Pinaki Mukherjee, Priyanka Manchanda, Pankaj Kumar, Lin Zhou, Matthew J. Kramer, Arti Kashyap, Ralph Skomski, David Sellmyer, Jeffrey E. Shield

Research output: Contribution to journalArticle

28 Scopus citations

Abstract

Formation of chemically ordered compounds of Fe and Au is inhibited in bulk materials due to their limited mutual solubility. However, here we report the formation of chemically ordered L12-type Fe3Au and FeAu3 compounds in Fe-Au sub-10 nm nanoparticles, suggesting that they are equilibrium structures in size-constrained systems. The stability of these L12-ordered Fe3Au and FeAu3 compounds along with a previously discovered L10-ordered FeAu has been explained by a size-dependent equilibrium thermodynamic model. Furthermore, the spin ordering of these three compounds has been computed using ab initio first-principle calculations. All ordered compounds exhibit a substantial magnetization at room temperature. The Fe3Au had a high saturation magnetization of about 143.6 emu/g with a ferromagnetic spin structure. The FeAu3 nanoparticles displayed a low saturation magnetization of about 11 emu/g. This suggests a antiferromagnetic spin structure, with the net magnetization arising from uncompensated surface spins. First-principle calculations using the Vienna ab initio simulation package (VASP) indicate that ferromagnetic ordering is energetically most stable in Fe3Au, while antiferromagnetic order is predicted in FeAu and FeAu3, consistent with the experimental results.

Original languageEnglish (US)
Pages (from-to)8113-8120
Number of pages8
JournalACS Nano
Volume8
Issue number8
DOIs
StatePublished - 2014

Keywords

  • Fe-Au
  • chemical ordering
  • nanomagnetism
  • nanoparticles
  • thermodynamics

ASJC Scopus subject areas

  • Materials Science(all)
  • Engineering(all)
  • Physics and Astronomy(all)

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  • Cite this

    Mukherjee, P., Manchanda, P., Kumar, P., Zhou, L., Kramer, M. J., Kashyap, A., Skomski, R., Sellmyer, D., & Shield, J. E. (2014). Size-induced chemical and magnetic ordering in individual Fe-Au nanoparticles. ACS Nano, 8(8), 8113-8120. https://doi.org/10.1021/nn5022007