Structure of ultrathin heteroepitaxial superconducting YBa2Cu3O7−x films

Abstract

The atomic structures of ultrathin YBa2Cu3O7−x (YBCO) films on SrTiO3(001) (STO) and (LaxSr1−x)(AlyTa1−y)O3(001) (LSAT) were investigated with sub-Angstrom resolution using surface x-ray diffraction and the phase-retrieval direct-method difference map using the constraints of atomicity and film shift (DCAF). The model-independent electron densities which emerge from random initializations in DCAF are exceedingly stable. The films grow with a well-defined stacking sequence even when grown on substrates with mixed terrace termination. Only very minor out-of-plane deviations from bulk YBCO are observed in the film structures, although they are perfectly strained to the substrate and are therefore tetragonal. The films are superconducting, with critical temperatures for growth on STO and LSAT of 43 K and 70 K, respectively. These results have important implications for reliable structure determination of technologically relevant complex-metal oxide surfaces and interfaces.

Source-reported materials — not catalogue approval

Similar papers