Band structure of Bi2Sr2CuO6: Strong effects due to structural modulation

The electronic structure of idealized tetragonal Bi₂Sr₂CuO₆ is compared with that of an orthorhombic 2×2 model that includes atomic displacements due to the structural modulation. The electronic structure, particularly that related to Bi and O(3) atoms, is strongly modified near the Fermi energy. In particular the shape and topology of the Bi-O(3) related Fermi surfaces near the ¯M point are changed. With the modulation, bands occur near the Fermi energy over a significant part of the zone near this point. A method is proposed to distinguish between lattice distortions and antiferromagnetic correlations as the cause of recently observed shadow Fermi surfaces.