Figure 1

Structural characteristics of the La–Ca–Cu–O film. (a) A unit cell of the spin-chain ladder cuprate La₅Ca₉Cu₂₄O₄₁ and a Cu₂O₃ layer with spin ladders. The crystal structures are drawn using VESTA²⁷ and referring to the structural data²⁸. (b) XRD patterns and (c) Raman spectra of the as-sputtered and heat-treated (400 s at 700 °C) films and polycrystalline La₅Ca₉Cu₂₄O₄₁ synthesized by a solid-state reaction method¹⁷. (d,e) Surface morphology obtained by DFM of the as-sputtered and heat-treated films.