Interdependence Between Training and Magnetization Reversal in Granular Co-CoO Exchange Bias Systems

Published

April 9, 2014

Author(s)

E. Menendez, T. Dias, J. Geshev, J. F. Lopez-Barbera, J. Nogues, R. Steitz, Brian Kirby, Julie Borchers, L.M.C. Pereira, A. Vantomme, K. Temst

Abstract

The interdependence between training and magnetization reversal in granular Co-CoO exchange bias systems prepared by O ion implantation in Co thin films is demonstrated by polarized neutron reflectometry. The implantations result in rather uniform O depth distributions. While high-fluence O-implanted thin films show reduced relative training values and no asymmetry in magnetization reversal (all reversals take place by domain wall nucleation and motion), low-fluence O ion implantation results in an increased relative training and a magnetization reversal asymmetry between the first descending and the first ascending (i.e., 2^nd reversal) virgin branches. Whereas the first untrained reversal occurs mainly by domain wall nucleation and motion, traces of a domain rotation contribution are evidenced in the second untrained reversal. This is explained by the evolution of the CoO structure and the contribution of the out-of-plane magnetization with ion implantation. The amount of incorporated O, which determines the threshold of both behaviors, is around 20 at. %. This reveals that the interdependence between training and magnetization reversal is insensitive to the morphology of the constituents (i.e., granular or layered), indicating that this is an intrinsic exchange bias effect, which can be conveniently tailored by the interplay between the intrinsic properties of the investigated materials and ion implantation.

Citation

Physical Review B

Volume

89

Issue

14

Pub Type

Journals

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Keywords

exchange bias

Citation

Menendez, E. , Dias, T. , Geshev, J. , Lopez-Barbera, J. , Nogues, J. , Steitz, R. , Kirby, B. , Borchers, J. , Pereira, L. , Vantomme, A. and Temst, K. (2014), Interdependence Between Training and Magnetization Reversal in Granular Co-CoO Exchange Bias Systems, Physical Review B, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=915990 (Accessed December 11, 2024)