STM/STS study on nondispersive checkerboard superstructure in superconducting Bi2212 and La-Bi2201

We performed STM/STS measurements on superconducting Bi2212 and La-Bi2201 in order to study the nondispersive two-dimensional (2D) electronic superstructure, namely the so-called checkerboard. The nondispersive checkerboard clearly appears within the pairing gap in both systems, although the period is different between Bi2212 (∼4a×4a∼4a×4a) and La-Bi2201 (∼5a×5a∼5a×5a). We point out that the nondispersive checkerboard originates in hole-pairs and/or quasiparticles around the antinodes of the d-wave gap, and interrelates with the spatially inhomogeneous pairing gap.