Research Papers in Physics and Astronomy

 

Date of this Version

10-30-2007

Comments

Published in APPLIED PHYSICS LETTERS 91, 172506 (2007). DOI: 10.1063/1.2801519 Copyright © 2007 American Institute of Physics. Used by permission.

Abstract

Moderate dc magnetic fields of less than 1 T allow tuning the exchange bias in an epitaxially grown Fe 10 nm/Cr2O3 2.7 nm/Fe 10 nm trilayer between negative and positive bias fields. Remarkably, this tunable exchange bias is observed at least up to 395 K which exceeds the Néel temperature of bulk Cr2O3 (307 K). The presence of spontaneous exchange bias and the absence of training effects at room temperature suggest the existence of stable interface moments independent of antiferromagnetic long range order in Cr2O3. Furthermore, the coercivity remains constant, independent of the exchange bias field. In contrast, large training associated with nonequilibrium spin configurations of antiferromagnetically ordered Cr2O3 appears below 50 K.

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