Fig. 5: High-angle annular dark-field (HAADF) scanning transmission electron microscopy (STEM) images of Sample 1 (Sr₂MnO₂Cu_0.35Li_0.13S₂).

a Close-up view displaying intergrowth of [100] and [010] zones of the collapsed phase (See Supplementary Fig. 23 for the whole image). The structure of the C2/m model (Fig. 2b) was overlaid for comparison. b Close-up view of the domain where the collapsed-type layers intergrow with the parent-type layers. White arrows highlight darker and thinner strips that represent the metal-free layers of disulphide ions. Between the collapsed-type layers, Sr₂MnO₂ slabs shift either left or right (highlighted by red or blue lines, respectively). The overlaid image depicts the tentative structure model of the intergrowth domain, where structural parameters within the respective intergrowing slabs are fixed to those of the C2/m model and Sr₂MnO₂Cu_1.5S₂³⁰. See Supplementary Fig. 24 for details. c, d Structural parameters obtained from the convoluted intensity profile (Supplementary Fig. 25) of Fig. 5a, b. The distances between planes of Sr²⁺ ions are shown.