Abstract

We report on the observation of the effects of exchange bias on the magnetization reversal processes in a [Co/CoO/Au]₂₀ system using polarized neutron reflectometry (PNR). The focus in this study is the investigation of the off-specular scattering of neutrons from magnetic domain structures during the magnetization reversal. In a previous PNR study on the same system, an asymmetry in magnetization reversal has been observed on opposite sides of the same hysteresis loop. For the decreasing field branch, the reversal was found to be dominated by domain wall motion of domains directed parallel or antiparallel to the applied field. In contrast, the reversal on the increasing field branch was characterized by rotation of magnetization. A significant loss of intensity was found for the specular reflected neutrons, while off-specular scattering experiments reveal that this magnetization reversal is not determined by coherent rotation but rather by a breaking up into smaller domains with different orientations.

Keywords: Exchange bias; Polarized neutron reflectometry; Off-specular scattering

PACS: 75.70.Ak; 75.30.Gw; 75.70.Cn

Article Outline

1. Introduction

2. Experimental procedures

3. Results

4. Conclusions

References

(70K)
Fig. 1. Intensity maps (for incoming (−) neutrons) recorded at different characteristic fields. Top: saturation; middle: H=−883 Oe close to H_CA; H=112 Oe close to H_CP. The dashed lines indicate the specularly reflected intensity, which is plotted below each map as a function of the incident angle.

(31K)
Fig. 2. Rocking scans with spin analysis at magnetic saturation (top), at H=−888 Oe close to H_CA (middle) and at 114 Oe close to H_CP. Full square symbols represent NSF-reflectivities, open symbols SF reflectivities. Solid and dashed lines which schematically indicate background and diffuse intensities are guides to the eyes only.

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