Strain accommodation through facet matching in La₁.85Sr₀.15CuO₄/Nd₁.85Ce₀.15CuO₄ ramp-edge junctions

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Scanning nano-focused X-ray diffraction (nXRD) and high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) are used to investigate the crystal structure of ramp-edge junctions between superconducting electron-doped Nd₁.85Ce₀.15CuO₄ and superconducting hole-doped La₁.85Sr₀.15CuO₄ thin films, the latter being the top layer. On the ramp, a new growth mode of La₁.85Sr₀.15CuO₄ with a 3.3 degree tilt of the c-axis is found. We explain the tilt by developing a strain accommodation model that relies on facet matching, dictated by the ramp angle, indicating that a coherent domain boundary is formed at the interface. The possible implications of this growth mode for the creation of artificial domains in morphotropic materials are discussed.