Structure and magnetism of Mn5Ge3 nanoparticles

Onur Tosun, Mohammed Salehi-Fashami, Balamurugan Balasubramanian, Ralph Skomski, David J. Sellmyer, George C. Hadjipanayis

Research output: Contribution to journalArticle

3 Scopus citations

Abstract

In this work, we investigated the magnetic and structural properties of isolated Mn5Ge3 nanoparticles prepared by the cluster-beam deposition technique. Particles with sizes between 7.2 and 12.6 nm were produced by varying the argon pressure and power in the cluster gun. X-ray diffraction (XRD)and selected area diffraction (SAD) measurements show that the nanoparticles crystallize in the hexagonal Mn5Si3-type crystal structure, which is also the structure of bulk Mn5Ge3. The temperature dependence of the magnetization shows that the as-made particles are ferromagnetic at room temperature and have slightly different Curie temperatures. Hysteresis-loop measurements show that the saturation magnetization of the nanoparticles increases significantly with particle size, varying from 31 kA/m to 172 kA/m when the particle size increases from 7.2 to 12.6 nm. The magnetocrystalline anisotropy constant K at 50 K, determined by fitting the high-field magnetization data to the law of approach to saturation, also increases with particle size, from 0.4 × 105 J/m3 to 2.9 × 105 J/m3 for the respective sizes. This trend is mirrored by the coercivity at 50 K, which increases from 0.04 T to 0.13 T. A possible explanation for the magnetization trend is a radial Ge concentration gradient.

Original languageEnglish (US)
Article number241
JournalNanomaterials
Volume8
Issue number4
DOIs
StatePublished - Apr 15 2018

Keywords

  • Cluster deposition
  • Magnetic nanoparticles
  • Magnetization

ASJC Scopus subject areas

  • Chemical Engineering(all)
  • Materials Science(all)

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    Tosun, O., Salehi-Fashami, M., Balasubramanian, B., Skomski, R., Sellmyer, D. J., & Hadjipanayis, G. C. (2018). Structure and magnetism of Mn5Ge3 nanoparticles. Nanomaterials, 8(4), [241]. https://doi.org/10.3390/nano8040241