Manipulating the magnetic structure of Co Core/CoO shell nanoparticles: Implications for controlling the exchange bias

被引：94

作者：

Inderhees, S. E. ^{[1
]}

Borchers, J. A. ^{[2
]}

Green, K. S. ^{[1
]}

Kim, M. S. ^{[1
,3
]}

Sun, K. ^{[1
]}

Strycker, G. L. ^{[1
]}

Aronson, M. C. ^{[1
,3
]}

机构：

[1] Univ Michigan, Ann Arbor, MI 48109 USA

[2] NIST, Gaithersburg, MD 20899 USA

[3] Brookhaven Natl Lab, Upton, NY 11973 USA

来源：

PHYSICAL REVIEW LETTERS | 2008年 / 101卷 / 11期

关键词：

D O I：

10.1103/PhysRevLett.101.117202

中图分类号：

O4 [物理学];

学科分类号：

0702 ;

摘要：

We present an experimental study of the effects of oxidation on the magnetic and crystal structures of exchange biased epsilon-Co/CoO core-shell nanoparticles. Transmission electron microscopy measurements reveal that oxidation creates a Co-CoO interface which is highly directional and epitaxial in quality. Neutron diffraction measurements find that below a Neel temperature T-N of similar to 235 K the magnetization of the CoO shell is modulated by two wave vectors, q(1)= (1/2 1/2 1/2)2 pi/alpha and q(2) = (100)2 pi/alpha. Oxidation affects the q(1) component of the magnetization very little, but hugely enhances the q(2) component, resulting in the magnetic decompensation of the core-shell interface. We propose that the large exchange bias effect results from the highly ordered interface between the Co core and CoO shell, and from enhanced core-shell coupling by the uncompensated interface moment.

引用

页数：4

共 30 条

[1] Finite-size effects and uncompensated magnetization in thin antiferromagnetic CoO layers [J].