Dirac Fermions in Graphene and Graphiteâa view from angle ...

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Figure 7.8. (a) ARPES intensity map taken on HOPG sample at 26 eV photon energy (k z ≈ 0.13 c ∗ ). (b) ARPES intensity map measured at the same conditions as panel a except on a different spot inside the sample. The arrow points to the additional intensity near E F . (c) ARPES intensity map measured on single crystal graphite with 50 eV photon energy. The dotted line is extracted dispersion from EDCs. (d) ARPES intensity maps measured at the same conditions as panel c except on a different spot. The dotted line is the dispersion extracted from panel c. The open circles are the dispersions extracted for the additional feature at low energy. 7.6 Conclusions and implication of this study We report clear evidence that sharp quasiparticle dispersions, in agreement with band structure calculation along the high symmetry directions, can coexist with a circular Fermi energy intensity map, a definitive signature of azimuthal disorder 124 . The measured dispersions from HOPG are compared with those measured from single crystal graphite. The good agreement between data taken on these two different kinds of samples suggests that more ARPES opportunities can be made available for layered materials even when high quality single crystals of large size are difficult to obtain. A typical example of such samples is the recently discovered superconducting C 6 Ca 97 , where intercalation is more favorable in HOPG than in single crystalline graphite, thus the resulting superconducting C 6 Ca is azimuthally disordered. This study suggests that even with such an azimuthally disordered sample, it is still promising to study with ARPES to obtain useful information. 59
Figure 7.9. (a) ARPES intensity map taken at 26 eV photon energy (k z = 0.13 c ∗ ) from a HOPG sample. Red and blue circles are the dispersions extracted from EDCs for the electron-like band and π bands, while the dotted black line is the dispersion extracted from MDCs. (b) MDC at E F . Blue, red and gray dotted lines are the peaks used to fit the MDC. (c) MDC at -0.1 eV. (d) EDCs taken at momenta from k 0 to k 15 indicated by vertical tick marks on the top of panel a. The EDCs at k 0 to k 5 are scaled by different factors so that all the peaks can be seen. (e-g) EDCs at k 1 , k 7 , k 12 . 60
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Dirac Fermions in Graphene and Grap
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Dirac Fermions in Graphene and Grap
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Contents Abstract 1 Contents Acknow
Page 7 and 8:
7.6 Conclusions and implication of
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Curriculum Vitæ Shuyun Zhou Educat
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• Selected as Science Highlight f
Page 13 and 14:
The unit cell of graphene contains
Page 15 and 16:
Projecting this equation into φ(r
Page 17 and 18:
Figure 1.5. Schematic drawing of th
Page 19 and 20: Chapter 2 Experimental techniques 2
Page 21 and 22: dispersion E(k z ). Thus k z values
Page 23 and 24: where ɛ is infinitely small. Accor
Page 25 and 26: Langmuirs (1L=10 −6 torr·s) to c
Page 27 and 28: mean free path, E kin is the kineti
Page 29 and 30: a b c d e f graphite SiC f graphite
Page 31 and 32: Figure 3.3. XPS results showing dat
Page 33 and 34: Figure 3.5. Intensity map at -1 eV
Page 35 and 36: Chapter 4 Gap opening in epitaxial
Page 37 and 38: Figure 4.2. Observation of the gap
Page 39 and 40: the EDCs as well as the region of e
Page 41 and 42: Figure 4.7. Dispersions measured in
Page 43 and 44: Figure 4.9. (a-c) LEEM images taken
Page 45 and 46: Figure 4.10. Proposed mechanism for
Page 47 and 48: Chapter 5 Metal-insulator transitio
Page 49 and 50: Figure 5.2. (a) Dispersions through
Page 51 and 52: Figure 5.3. (a-f) Data taken throug
Page 53 and 54: Chapter 6 Dirac fermions and effect
Page 55 and 56: Figure 6.2. Linear Λ-shaped disper
Page 57 and 58: Figure 6.4. Detailed low energy dis
Page 59 and 60: Figure 6.6. Detailed dispersion nea
Page 61 and 62: Chapter 7 ARPES study of partially
Page 63 and 64: Figure 7.2. (a) Fermi energy intens
Page 65 and 66: direction, i.e. perpendicular to gr
Page 67 and 68: Figure 7.5. ARPES intensity map mea
Page 69: Figure 7.7. (a) ARPES intensity map
Page 73 and 74: 19. Hüfner, S. Photoelectron Spect
Page 75 and 76: 59. Jiang, Y. J., Yao, D.-Y., Carls
Page 77 and 78: 99. Luk’yanchuk, I. A. & Kopelevi
Page 79 and 80: List of Figures 1.1 (a) Sp 2 bondin
Page 81 and 82: 4.8 Thickness dependence of E D and
Page 83 and 84: 7.2 (a) Fermi energy intensity map.
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