Exchange bias in Fe/Fe3O4 core-shell magnetic nanoparticles mediated by frozen interfacial spins

被引：295

作者：

Ong, Quy Khac ^{[1
]}

Wei, Alexander ^{[1
]}

Lin, Xiao-Min ^{[2
]}

机构：

[1] Purdue Univ, Dept Chem, W Lafayette, IN 47907 USA

[2] Argonne Natl Lab, Ctr Nanoscale Mat, Argonne, IL 60439 USA

来源：

PHYSICAL REVIEW B | 2009年 / 80卷 / 13期

基金：

美国国家科学基金会;

关键词：

FE NANOPARTICLES; BILAYERS; ANISOTROPY; DISORDER; SYSTEM; GLASS;

D O I：

10.1103/PhysRevB.80.134418

中图分类号：

T [工业技术];

学科分类号：

08 ;

摘要：

The magnetization curves of monodisperse Fe/Fe3O4 core-shell and Fe3O4 hollow-shell nanoparticles reveal an unusual exchange-bias effect. Hysteresis measurements of core-shell particles at 5 K after field cooling exhibit a large loop shift associated with unidirectional anisotropy whereas Fe3O4 hollow-shell nanoparticles support much smaller shifts. Both core-shell and hollow-shell particles exhibit sharp demagnetization jumps at low fields associated with a sudden switching of shell moments. Temperature-dependent magnetization of core-shell particles at high fields shows a deviation between field-cooled and zero-field-cooled curves below 30 K, suggesting the presence of frozen spins at the interface. These frozen interfacial spins play an important role in mediating the exchange coupling between the ferromagnetic core and ferrimagnetic shell.

引用

页数：6

共 36 条

[1] Exchange bias using a spin glass [J].