Structural and compositional characterization of (YBa₂Cu₃O₇)_m/ (PrBa₂Cu₃O₇)_n superlattices by means of high-resolution electron microscopy

The structural and compositional properties of (YBa₂Cu₃O₇)_m/ (PrBa₂Cu₃O₇)_n (m=1, n=6 and m=4, n=4) superlattices produced by high-pressure oxygen DC-sputtering were investigated by high-resolution transmission electron microscopy employing a chemically sensitive imaging technique. The width of the growth terraces of the individual layers indicates a relatively smooth surface of the sputtered films which grow in a two-dimensional growth mode. Interface steps and antiphase boundaries exist in both superlattices. In the 1×6 superlattice these defects critically disturb the continuity and superconducting qualities of the single-unit-cell layers of YBa₂Cu₃O₇. From the contrast analysis it can be concluded that interdiffusion between YBa₂Cu₃O₇ and PrBa₂Cu₃O₇ layers must be very low.