A Structural Viewpoint of Magnetism in Fe and Co Based Superlattices

In order to understand the properties of thin film devices, knowledge of the material’s structure is essential. The work presented here combines magnetic and structural characterization of the systems studied to gain a deeper physical understanding. The magnetic properties have been studied with a combination of x-ray magnetic circular dichroism, SQUID magnetometry and magneto-optical Kerr effect. For the structural characterization, x-ray reflectivity and diffraction have been used, complemented by neutron diffraction and transmission electron microscopy.One structural property that affects the magnetic moment in metal-on-metal superlattices is interdiffusion between the layers. This is discussed for bcc Fe/Co(001) and bcc Fe81Ni19/Co(001) superlattices. The effect of interdiffusion was seen as a large region of enhanced magnetic moments as compared to theoretical calculations, which assume perfectly sharp interfaces. For the Fe81Ni19/Co(001) superlattices the chemical interface region, as revealed by neutron diffraction, was in good agreement with the region of magnetic enhancement…


1 Introduction
2 Layer Growth
2.1 Sputtering
2.2 Film Growth
2.2.1 Crystalline Defects
2.2.2 Layer Imperfections
3 Thin Film Magnetism
3.1 Itinerant Ferromagnetism
3.2 Magnetic Moment
3.2.1 Thin Films
3.3 Anisotropy
3.3.1 Magnetocrystalline Anisotropy
3.3.2 Magnetoelastic Anisotropy
3.3.3 Interface Effects
3.3.4 Shape Anisotropy and Domains
4 Structural Characterization
4.1 Reciprocal Space
4.2 Diffraction from a Superlattice
4.3 Reflectivity
4.3.1 Layer Imperfection Models
4.3.2 Specular Reflectivity
4.3.3 Nonspecular Reflectivity
4.4 X-rays and Neutron
5 Magnetic Characterization
5.1 X-ray Magnetic Circular Dichroism
5.1.1 The Sum Rule
5.2 MOKE
5.3 Neutron Scattering
6 Summary of Results
6.1 Magnetic Moments and Interfaces
6.2 Magnetism and Strain
6.3 Conclusions and Outlook
7 Acknowledgments
Manual for GenX
Swedish Summary

Author: Bjorck, Matts

Source: Uppsala University Library

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