(Downloads - 0)
For more info about our services contact : help@bestpfe.com
Table of contents
1. Introduction
2. Spin-Polarized Tunneling and Spin Filtering
2.1 Spin-Polarized Tunneling
2.1.1 The Basics
2.1.2 Detecting Spins
2.1.3 Tunneling Magnetoresistance
2.2 Spin Filtering
2.2.1 Phenomenological Origin
2.2.2 Measurement Techniques
2.3 The Diverse Spectrum of Spin Filter Materials
2.3.1 Eu Chalcogenides
2.3.2 Perovskites
2.3.3 Ferrites
2.4 CoFe2O4 : A New Candidate for Room Temperature Spin
2.4.1 Structure
2.4.2 Magnetism
2.4.3 Electronic Band Structure
3. Experimental Methods : From thin film growth to spin-polarized tunneling
3.1 Epitaxial Growth of Spinel Ferrite Thin Films
3.1.1 Molecular Beam Epitaxy
3.1.2 Growth Conditions
3.2 In situ Characterization
3.2.1 Reflection High Energy Electron Diffraction
3.2.2 Electron Spectroscopies
3.3 Structural and Chemical Characterization Electron Microscopies
3.3.1 Transmission Electron Microscopy
3.3.2 Geometric Phase Method
3.3.3 Electron Energy Loss Spectroscopy
3.4 Magnetic Characterization
3.4.1 Vibrating Sample Magnetometry
3.4.2 Polarized Neutron Reflectometry
3.5 Electronic Transport and Spin-Polarized Tunneling
3.5.1 In-plane electronic transport
3.5.2 Two Terminal Versus Four Terminal Measurements
3.5.3 Sample Preparation for TMR Experiments : Optical Lithography
3.5.4 Out-of-plane Electronic Transport
3.5.5 Sample Preparation for Meservey-Tedrow Experiments
3.5.6 The Meservey-Tedrow Experiment
4. Characterization of CoFe2O4 Thin Films and Associated Multilayers
4.1 CoFe2O4 Single Layers
4.1.1 Epitaxial Growth : RHEED In situ
4.1.2 In situ Chemical Characterization by XPS
4.1.3 X-ray Diffraction and Reflectivity
4.1.4 X-ray Absorption and X-ray Magnetic Circular Dichroism
4.1.5 Growth on a Pt(111) buffer layer
4.2 CoFe2O4/Fe3O4 Bilayers
4.2.1 RHEED and XPS
4.2.2 Microscopy studies of CoFe2O4/Fe3O4
4.3 CoFe2O4/γ-Al2O3/Co trilayers and their variants
4.3.1 Epitaxial growth and RHEED
4.3.2 In situ spectroscopies : XPS and AES
4.3.3 TEM
5. CoFe2O4 single layer spin-filter tunnel barriers
5.1 Magnetic Properties of CoFe2O4 single layers
5.1.1 Magnetism in “thick” CoFe2O4 films
5.1.2 Magnetism in ultra-thin CoFe2O4 films
5.1.3 Optimization with a Pt(111) buffer layer
5.1.4 Magnetic properties of CoFe2O4/γ-Al2O3 double tunnel barriers
5.1.5 Low temperature SQUID measurements
5.2 In-plane Electronic Transport Measurements
5.3 Spin-polarized Tunneling in CoFe2O4 : Meservey-Tedrow Technique
5.3.1 The initial Meservey-Tedrow measurement
5.3.2 Optimizing the SPT results : Effect of oxidation
5.3.3 Junction Resistance Temperature Dependence
5.3.4 Discussion
6. CoFe2O4/Fe3O4 bilayers for spinel-based tunnel junctions
6.1 Magnetic Properties of the CoFe2O4/Fe3O4 system
6.1.1 Room temperature magnetization curves
6.1.2 Low temperature magnetization curves
6.1.3 Insertion of a thin γ-Al2O3 spacer
6.1.4 In-plane Magnetoresistance Measurements
6.1.5 Polarized Neutron Reflectivity
6.2 Discussion of the Exchange Coupling Mechanism
6.2.1 Switching Order
6.2.2 Nature of the Exchange Interaction
6.2.3 Local Magnetic Configuration at the Interface
7. CoFe2O4-based Magnetic Tunnel Junctions with cobalt electrodes .
7.1 Magnetic Characterization
7.1.1 CoFe2O4/Co bilayers
7.1.2 CoFe2O4/γ-Al2O3/Co trilayers
7.2 Tunneling Experiments
7.2.1 Resistance Measurements and TMR
7.2.2 Current-Voltage Characteristics
7.2.3 TMR versus Bias Voltage
7.2.4 Discussion
8. Conclusions and Future Work
8.1 Conclusions
8.1.1 Growth and materials characterization
8.1.2 Magnetism
8.1.3 Spin-polarized tunneling
8.2 Short-term Future Work
8.2.1 Meservey-Tedrow experiments on CoFe2O4 single layers
8.2.2 CoFe2O4/Fe3O4 bilayers and MTJs
8.2.3 Pt/CoFe2O4/γ-Al2O3/Co MTJs
8.3 Long-term Perspectives and Applications
8.3.1 Double spin filter tunnel junctions
8.3.2 Spin injection into semiconductors and organics
14 Contents
Appendix
A. Crystalline Co/α-Al2O3(0001) bilayers for fully epitaxial magnetic tunnel junctions
A.1 Epitaxial Growth and Materials Characterization
A.2 Spin-Polarized Tunneling Experiments
A.3 Conclusion
