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Zusammenfassung:
Research on high-temperature superconducting cuprates is at present focused on identifying the relationship between the classic ` pseudogap' phenomenon(1,2) and the more recently investigated density wave state(3-13). This state is generally characterized by a wavevector Q parallel to the planar Cu-O-Cu bonds(4-13) along with a predominantly d-symmetry form factor(14-16) (dFF-DW). To identify the microscopic mechanism giving rise to this state(17-29), one must identify the momentum-space states contributing to the dFF-DW spectral weight, determine their particle-hole phase relationship about the Fermi energy, establish whether they exhibit a characteristic energy gap, and understand the evolution of all these phenomena throughout the phase diagram. Here we use energy-resolved sublattice visualization(14) of electronic structure and reveal that the characteristic energy of the dFF-DW modulations is actually the 'pseudogap' energy Delta 1. Moreover, we demonstrate that the dFF-DW modulations at E = -Delta(1) (filled states) occur with relative phaseffcompared to those at E = -Delta(1) (empty states). Finally, we show that the conventionally defined dFF-DW Q corresponds to scattering between the ` hot frontier' regions of momentum-space beyond which Bogoliubov quasiparticles cease to exist(30-32). These data indicate that the cuprate dFF-DW state involves particle-hole interactions focused at the pseudogap energy scale and between the four pairs of ` hot frontier' regions in momentum space where the pseudogap opens.
