CONTENTS


1. Introduction and project objectives
References


2. Magnetism in Rare Earth and Laves Phase materials
          2.1. The origin of spontaneous magnetisation
                    2.1.1. The transition metals
                    2.1.2. The Lanthanides group
          2.2. Spin-orbit coupling and crystal fields in 3d and 4f metals
          2.3. The magnetic anisotropy of TM and RE elements
                    2.3.1. The magneto-crystalline anisotropy
                    2.3.2. The magneto-elastic effect
          2.4. The Laves phase materials
                    2.4.1. The Fe-Fe exchange interaction
                    2.4.2. The RE-RE exchange interaction
                    2.4.3. The RE-Fe exchange interaction
References


3. Growth of single crystal Laves phase superlattices
          3.1. Molecular beam epitaxy
                    3.1.1. Historical introduction
                    3.1.2. The principle of the MBE technique
          3.2. MBE growth of Laves phase based structures
                    3.2.1. The MBE instrument
                    3.2.2. The growth of epitaxial RE-Fe₂ structures
          3.3. Conclusions
References


4. Experimental methods
          4.1. The Vibrating Sample Magnetometer
          4.2. Preparation of the samples
References


5. Magnetic anisotropy of epitaxially strained Laves phase films
          5.1. Introduction
                    5.1.1. Thermal built-in strain
                    5.1.2. Substrate-film mismatch strain
                    5.1.3. Lattice mismatch strain
          5.2. Effect of thermal epitaxial strain on the magnetisation of (110) RE-Fe₂ thin
films
          5.3. Probing the easy axis of epitaxial RE-Fe₂ films with built-in strain
                    5.3.1. Epitaxial YFe₂ film
                    5.3.2. Epitaxial DyFe₂ film
                    5.3.2.a. Experimental results
                    5.3.2.b. Discussion
                    5.3.3. Epitaxial TbFe₂ film
          5.4. Conclusions
References


6. The coercivity of RE-Fe₂ multilayer and alloy films
          6.1. Introduction: the original expression of the Stoner and Wohlfarth model
          6.2. Modified form of the Stoner and Wohlfarth model
          6.3. The coercivity of MBE grown Tb_(1-x)Dy_xFe₂ alloys
                    6.3.1. Experimental results
                    6.3.2. Discussion and theory
          6.4. Engineering coercivity of DyFe₂ – YFe₂ multilayers
                    6.4.1. Experimental results
                    6.4.2. Discussion
          6.5. Conclusions
References


7. Magnetic exchange springs in DyFe₂ – YFe₂ multilayers
          7.1. Review of the research on magnetic exchange springs magnets
          7.2. Formation of a magnetic exchange springs feature in the YFe₂ layer
                    7.2.1. Experimental results
                    7.2.2. Discussion and theory
          7.3. Engineering magnetic exchange springs
                    7.3.1. Experimental results
                    7.3.2. The bending field B_B as a function of the YFe₂ layer thickness
          7.4. Conclusions
References


8. Influence of magnetic exchange springs on the coercive field
          8.1. Interfacial interactions
          8.2. The effect of the magnetic exchange springs on the magnetisation reversal mechanism
                    8.2.1. Experimental results
                    8.2.2. Discussion and theory
          8.3. Engineering negative coercivity in DyFe₂ – YFe₂ multilayer films
                    8.3.1. Experimental results
                    8.3.2. Discussion
          8.4. Metastable state in negative coercivity samples
                    8.4.1. Experimental results
                    8.4.2. Discussion
          8.5. Tailoring magnetically compensated DyFe₂ – YFe₂ superlattices
                    8.5.1. Experimental results and discussion
                    8.5.2. Possible practical application
          8.6. Conclusions
References


9. Summary
References


Appendix
          Conversion of the measured magnetisation in Bohr magneton per formula unit
          Estimation of the DW width of the DyFe₂ – YFe₂ multilayer films
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