Magnetocrystalline anisotropy of partially ordered Fe-Pt nanoparticles directly synthesized with microwave-polyol method

Author

Kitamoto, Yoshitaka ; Minami, Rumiko ; Shibata, Yuuki ; Chikata, Tsukasa ; Kato, Shunsaku

Author_Institution

Dept. of Innovative & Eng. Mater., Tokyo Inst. of Technol., Yokohama, Japan

Volume

41

Issue

10

fYear

2005

Firstpage

3880

Lastpage

3882

Abstract

We report direct synthesis of chemically ordered Fe-Pt nanoparticles using microwave irradiation during polyol reaction at 250°C without any post-synthesis treatments. Mössbauer analysis exhibits the Fe-Pt nanoparticles having partially ordered L1₀ structure, and the fraction of Fe atoms in the chemically ordered L1₀ structure to the total amount of Fe atoms is 57%. Coercivity and saturation magnetization of the partially ordered Fe-Pt nanoparticles are 3.0 kOe and 57 emu/g at room temperature, respectively. An evaluation of the anisotropy-field distribution using Flanders-Shtrikman method reveals that the Fe-Pt sample includes nanoparticles with anisotropy fields much lower than the anisotropy field H_k^Wr of 85 kOe obtained by rotational hysteresis loss measurements.

Keywords

Mossbauer spectroscopy; coercive force; ferromagnetic materials; magnetic anisotropy; magnetic particles; nanocomposites; nanoparticles; polymers; radiation effects; 250 C; FePt; Flanders-Shtrikman method; Mossbauer analysis; anisotropy field distribution; coercivity; magnetocrystalline anisotropy; microwave irradiation; nanoparticles; polyol reaction; post-synthesis treatments; rotational hysteresis loss measurements; saturation magnetization; Anisotropic magnetoresistance; Chemical analysis; Coercive force; Iron; Magnetic analysis; Magnetic anisotropy; Microwave theory and techniques; Nanoparticles; Perpendicular magnetic anisotropy; Saturation magnetization; MÖssbauer spectroscopy; Magnetization decay; magnetocrystalline anisotropy; nanoparticle; ordered alloy;

fLanguage

English

Journal_Title

Magnetics, IEEE Transactions on

Publisher

ieee

ISSN

0018-9464

Type

jour

DOI

10.1109/TMAG.2005.854953

Filename

1519475