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

doi:10.1016/S0921-4526(97)00979-4

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

Department of Chemistry

Research output: Contribution to journal › Article › peer-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/μ_B). However, magnetization measurements up to 35 T do not permit to reach saturation, and show a continuous increase of μ_Co reaching 2.1 ± 0.1μ_B (C1) and 1.9 ± 0.1μ_B (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 language	English
Pages (from-to)	532-536
Number of pages	5
Journal	Physica B: Condensed Matter
Volume	246-247
DOIs	https://doi.org/10.1016/S0921-4526(97)00979-4
Publication status	Published - 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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title = "Magnetization measurements on fine cobalt particles",

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.",

keywords = "Cobalt, Effective magnetic anisotropy, Fine particle, Magnetization",

author = "M. Respaud and Broto, {J. M.} and H. Rakoto and Ousset, {J. C.} and J. Osuna and {Ould Ely}, T. and C. Amiens and B. Chaudret and S. Askenazy",

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doi = "10.1016/S0921-4526(97)00979-4",

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T1 - Magnetization measurements on fine cobalt particles

AU - Respaud, M.

AU - Broto, J. M.

AU - Rakoto, H.

AU - Ousset, J. C.

AU - Osuna, J.

AU - Ould Ely, T.

AU - Amiens, C.

AU - Chaudret, B.

AU - Askenazy, S.

PY - 1998/5/29

Y1 - 1998/5/29

N2 - 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.

AB - 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.

KW - Cobalt

KW - Effective magnetic anisotropy

KW - Fine particle

KW - Magnetization

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