One-Dimensional Electronic Structure and Suppression of d -Wave Node State in (La 1.28 Nd 0.6 Sr 0.12 )CuO 4

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Abstract
Angle-resolved photoemission spectroscopy was carried out on (La 1.28 Nd 0.6 Sr 0.12 )CuO 4 , a model system of the charge- and spin-ordered state, or stripe phase. The electronic structure contains characteristic features consistent with other cuprates, such as the flat band at low energy near the Brillouin zone face. However, the low-energy excitation near the expected d -wave node region is strongly suppressed. The frequency-integrated spectral weight is confined inside one-dimensional segments in the momentum space (defined by horizontal momenta | k x | = π/4 and vertical momenta | k y | = π/4), deviating strongly from the more rounded Fermi surface expected from band calculations. This departure from the two-dimensional Fermi surface persists to a very high energy scale. These results provide important information for establishing a theory to understand the charge and spin ordering in cuprates and their relation with high-temperature superconductivity.