Competing interactions in dispersions of superparamagnetic nanoparticles

被引：141

作者：

Held, GA ^{[1
]}

Grinstein, G ^{[1
]}

Doyle, H ^{[1
]}

Sun, SH ^{[1
]}

Murray, CB ^{[1
]}

机构：

[1] IBM Corp, Thomas J Watson Res Ctr, Yorktown Hts, NY 10598 USA

来源：

PHYSICAL REVIEW B | 2001年 / 64卷 / 01期

关键词：

D O I：

10.1103/PhysRevB.64.012408

中图分类号：

T [工业技术];

学科分类号：

08 ;

摘要：

We study the magnetic properties of dispersions of uniformly sized, chemically synthesized cobalt nanoparticles (NP's), observing a crossover from a blocked state to a superparamagnetic one with increasing temperature. By analyzing magnetization data, we determine the distributions of NP volumes and anisotropies, and establish that variations in the shapes of the magnetic cores of the NP's generate the anisotropy governing the crossover. We characterize the frustrated low-temperature state produced by the competition between dipolar interactions and anisotropy at sufficiently high NP density through remanent magnetization measurements, and explain the results through analysis of a simple model.

引用

页数：4

共 23 条

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