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4.1. Coherent growth: EuO on YSZ (100) 61 moment (a.u.) -400 -200 0 200 400 0 20 40 60 80 100 120 140 temperature (K) -400 -200 0 200 400 Figure 4.2.: Electron diffraction pattern for EuO thin films for different oxygen partial pressures during growth. From (a)to(d), the oxidation of EuO during synthesis is reduced, and RHEED (blue), LEED (green), and SQUID results display the effects of stoichiometry variation. The EuO films are synthesized on annealed YSZ (100) at T S = 400 ◦ C and are ∼20 nm thick.
62 4. Results I: Single-crystalline epitaxial EuO thin films on cubic oxides Figure 4.3.: Bulk and interface morphology of EuO on conductive YSZ (100) observed by transmission electron microscopy. (a) A region of the perpendicularly cut lamella of a Cu/EuO/cYSZ heterostructure. A magnification of the EuO/cYSZ interface is included in the right panel. In (b) fast Fourier transforms of the EuO film and the cYSZ substrate depict the reciprocal lattice. (c) shows the intensity profile of a section normal to the EuO/cYSZ interface which allows to determine the lattice parameter. Next, we investigate the crystalline homogeneity of the magnetic oxide (5 nm EuO) and the structure of the EuO/cYSZ (100) interface. High resolution electron transmission microscopy pictures (HR-TEM) of a representative Cu/EuO/YSZ(100) heterostructure are depicted in Fig. 4.3. Sharp interfaces between EuO and the YSZ substrate as well as between EuO and the metallic Cu capping are found in the entire heterostructure. We see no structural defects in the EuO magnetic oxide layer, and a clear fcc reciprocal lattice is found by a fast Fourier transformation of the electron micrograph. Finally, an intensity profile perpendicular to the EuO/YSZ interface reveals a homogeneous spacing of the EuO net planes which exhibit the same lattice parameter as the YSZ. This is a confirmation of the structural homogeneity of EuO in growth direction. In lateral direction (parallel to the interface), Eu sites of EuO match the YSZ cubic lattice sites, which is an evidence for cube-on-cube epitaxy. Remarkably, also the Cu/EuO (100) interface shows the lateral lattice planes in same directions. This may be a promising route for a future epitaxial integration of Cu with EuO (100). † This heterostructure uses already the conductive YSZ substrate (cYSZ), which permits one to use highelectron yield techniques without charging issues. This is discussed in the following section. † Epitaxial EuO/Cu may be a promising system for coherent tunneling in the frame of symmetry band structures. See Ch. 2.3.3.
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Member of the Helmholtz Association
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Forschungszentrum Jülich GmbH Pete
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Zusammenfassung In dieser Doktorarb
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Contents 1. Introduction 1 2. Theor
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List of Figures 2.1. Phase diagram
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List of Figures xi 5.12. Resulting
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1. Introduction Smart and powerful
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3 In the thesis at ha
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2. Theoretical background . . . The
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2.1. The challenge of stabilizing s
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2.2. Electronic structure of EuO 9
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Page 60 and 61: 3.3. Experimental developments at t
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Page 76 and 77: 59 Table 4.1.: Parameters for stoic
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Page 122 and 123: 5.3. Interface engineering I: Hydro
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5.4. Interface engineering II: Eu p
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5.5. Interface engineering III: SiO
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5.5. Interface engineering III: SiO
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5.6. Summary 121
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6. Conclusion and Outlook In the th
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125 Outlook and perspectives In the
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A.1. EuO-related phases and cubic o
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A.1. EuO-related phases and cubic o
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A.2. In situ analysis of the Si (00
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Bibliography 133 [13] S. S. P. Park
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Bibliography 135 [36] R. E. Dickers
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Bibliography 137 [65] R. Sutarto, S
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Bibliography 139 [91] P. Braun, M.
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Bibliography 141 [116] S. Hüfner.
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Bibliography 143 [144] R. Feder and
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Bibliography 145 [171] H. Miyazaki,
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Bibliography 147 [197] J. Qi, T. Ma
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Software and Internet Resources [21
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List of own publications 151 [10] R
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List of conference contributions 15
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Schriften des Forschungszentrums J
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Schlüsseltechnologien / Key Techno
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