Proteresis in Co:CoO core-shell nanoclusters

Authors

X.-H. Wei, University of Nebraska-Lincoln
Ralph Skomski, University of Nebraska-LincolnFollow
Zhiguang Sun, University of Nebraska-LincolnFollow
David J. Sellmyer, University of Nebraska-LincolnFollow

Date of this Version

1-28-2008

Comments

Published by Am Inst of Physics. J. Appl. Phys. 103, 07D514 2008. Copyright 2008. Permission to use. http://www.aip.org/.

Abstract

The magnetism of ultrasmall Co:CoO core-shell nanoclusters is investigated. The structures, produced by cluster-beam deposition, have Co core sizes ranging from 1 to 7 nm and a CoO shell thickness of about 3 nm. Hysteresis loops as well as zero-field-cooled and field-cooled magnetization curves have been measured and a striking feature of the nanostructures is the existence of proteretic (clockwise) rather than hysteretic loops in the core-size range from 3 to 4 nm. The proteretic behavior and its particle-size dependence reflect a subtle interplay between various anisotropies and exchange interactions in the Co and CoO phases and at the Co–CoO interface.