Iron-Based Superconductivity by Peter D. Johnson Guangyong Xu & Wei-Guo Yin

Author:Peter D. Johnson, Guangyong Xu & Wei-Guo Yin
Language: eng
Format: epub
Publisher: Springer International Publishing, Cham

Figure 7.4 shows clearly that the anion bands within [ − 6, − 2] eV develop very strong shadows bands, of comparable intensity to the main bands. This reflects their strong coupling to the TSBP, as it is the alternating positioning of the anion that breaks the translational symmetry. Given that one can hardly distinguish the main bands from the shadow bands, it is obviously more convenient to consider these anion bands in the 2-Fe-atom Brillouin zone.

In great contrast, the Fe bands near the Fermi level have rather weak shadow bands. In fact, if it were not for the gap openings (some of which are quite large), the Fe bands would have looked just like those from a simple 5-band system. The overall weak intensity of shadow bands explains why neutron spectra appear to respect the 1-Fe-atom Brillouin zone: even though the real symmetry of the system dictates the 2-Fe-atom Brillouin zone, the folding of the spectrum is just not strong enough for a clear experimental identification. In fact, the lack of folded bands was also reported in a recent ARPES experiment [46]. Consequently, a larger 1-Fe-atom Brillouin zone is necessary in future ARPES measurements, since only about half of the EBSs are clearly observable in the 2-Fe BZ, where most ARPES to date were conducted.

Table 7.2Nearest-neighbor hopping integrals (in eV) along the x direction among Fe d Wannier orbitals for nonmagnetic

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