Magnetization measurements on fine cobalt particles

M. Respaud, J. M. Broto, H. Rakoto, J. C. Ousset, J. Osuna, T. Ould Ely, C. Amiens, B. Chaudret, S. Askenazy

Research output: Contribution to journalArticlepeer-review

13 Citations (Scopus)

Abstract

We measure the magnetization of fine cobalt particles by SQUID and pulsed magnetic fields up to 35 T. These measurements have been made on two samples (C1, C2) with nonagglomerated particles. The analysis of the magnetic meaurements evidences very narrow log-normal size distribution centered around 1.5nm (≅ 150 atoms) and 1.9 nm (≅ 310 atoms) for C1 and C2, respectively. Magnetization at 4.2 K seems to saturate in fields up to 5 T leading to an enhanced mean magnetic moment per atom compared to bulk value (1.72/μB). However, magnetization measurements up to 35 T do not permit to reach saturation, and show a continuous increase of μCo reaching 2.1 ± 0.1μB (C1) and 1.9 ± 0.1μB (C2). The effective magnetic anisotropies are found to be larger than those of bulk materials and decrease with increasing particle size. These features are associated with the large influence of the surface atoms.

Original languageEnglish
Pages (from-to)532-536
Number of pages5
JournalPhysica B: Condensed Matter
Volume246-247
DOIs
Publication statusPublished - May 29 1998

Keywords

  • Cobalt
  • Effective magnetic anisotropy
  • Fine particle
  • Magnetization

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Electrical and Electronic Engineering

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