Figure 1: In-plane component of the electronic supermodulation.
(a) Schematic of the heterostructure in sample #1. The individual atomic layers (AO and BO2) of the ABO3-type perovskite are indicated by different colours. (b) X-ray absorption spectrum measured near the Cu L3 absorption edge in total fluorescence yield. Main configuration-dependent contributions to the spectrum are marked by red and grey bars as reproduced from ref. 13. Red and grey bars mark the energy positions of states derived from the Cu sites in the CuO2 plane (Cu2) and those in the Cu–O chain layer (Cu1), respectively. Inset: schematic of the scattering geometry with linear (π) incident polarization in the horizontal scattering plane. (c) In-plane reciprocal space projection derived from a single CCD image measured at 930.85 eV (indicated by blue arrow in b) showing a diffraction peak near (−0.245, 0, 1.38). Note that the raw image contains the L range from ∼1.31 to ∼1.45, and only its projection onto the (H, K, 0) plane is shown here. (d,e) Scattered intensity line cuts along H measured at 50 K and 930.85 eV at fixed L=1.38 and K=0. Each point on the red (grey) curve indicates average intensity in the region of the corresponding CCD image marked by the red (grey) rectangle in c. Blue curve is the difference between red and grey curves showing the diffracted intensity. The intensity in e and diffracted intensity in d–f all share the same scale with the intensity in d. (f) Diffracted intensity measured at 926 eV (green curve, indicated by the green arrow in b) and 930.85 eV (blue curve, reproduced from e) at fixed L=1.38 and K=0, compared alongside the K scan of La1.875Ba0.125CuO4 (reproduced from ref. 21; note that equivalent modulations exist along both the H and K directions in the low-temperature tetragonal phase of La1.875Ba0.125CuO4). All results were obtained from sample #1. r.l.u., reciprocal lattice units.
