Dynamic magnetization of ε-Fe2O3 in pulse field: Evidence of surface effect

被引：43

作者：

Balaev, D. A. ^{[1
,2
]}

Poperechny, I. S. ^{[3
,4
]}

Krasikov, A. A. ^{[2
]}

Shaikhutdinov, K. A. ^{[1
]}

Dubrovskiy, A. A. ^{[1
]}

Popkov, S. I. ^{[1
]}

Balaev, A. D. ^{[1
]}

Yakushkin, S. S. ^{[5
]}

Bukhtiyarova, G. A. ^{[5
]}

Martyanov, O. N. ^{[5
]}

Raikher, Yu. L. ^{[3
,6
]}

机构：

[1] Russian Acad Sci, Siberian Branch, Kirensky Inst Phys, Krasnoyarsk 660036, Russia

[2] Siberian Fed Univ, Krasnoyarsk 660041, Russia

[3] Russian Acad Sci, Inst Continuous Media Mech, Ural Branch, Perm 614013, Russia

[4] Perm Natl Res Polytech Univ, Perm 614990, Russia

[5] Russian Acad Sci, Boreskov Inst Catalysis, Siberian Branch, Novosibirsk 630090, Russia

[6] Ural Fed Univ, Ekaterinburg 620083, Russia

来源：

JOURNAL OF APPLIED PHYSICS | 2015年 / 117卷 / 06期

关键词：

FERROMAGNETIC-RESONANCE; COERCIVE FIELD; NANOPARTICLES; IRON; REORIENTATION; ANISOTROPY; PARTICLES; FERRITE; PHASE; OXIDE;

D O I：

10.1063/1.4907586

中图分类号：

O59 [应用物理学];

学科分类号：

摘要：

The magnetization dynamics of epsilon-Fe2O3 nanoparticles with an average size of about 9nm is investigated. From comparison of the hysteresis loops obtained in quasi-static conditions and under pulse fields with amplitudes up to 200 kOe and pulse lengths 8-32ms, it follows that the effective coercivity increases considerably with the variation rate of the imposed magnetic field. A theoretical explanation of this behavior is proposed. The model takes into account the superparamagnetic effects as well as the fact that magnetic anisotropy of the nanoparticles, along with the bulk term, includes a surface contribution. The latter, being of minor importance for the observed magnetic behavior of 25-100nm particles, becomes essential when the particle size is below 10 nm. From the experimental data, a reference value of the surface anisotropy of nanodisperse epsilon-Fe2O3 is established, and evidence is presented to the effect that below 300K this contribution does not significantly depend on temperature. (C) 2015 AIP Publishing LLC.

引用

页数：6

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