Strain-induced structural transition in DyBa2Cu3O7−x films grown by atomic layer-by-layer molecular beam epitaxy
D. Putzky, P. Radhakrishnan, Y. Wang, P. Wochner, G. Christiani, M. Minola, P. A. van Aken, G. Logvenov, E. Benckiser, and B. Keimer
Applied Physics Letters 117, 072601 (2020)
We have used atomic layer-by-layer molecular beam epitaxy to synthesize coherently lattice-matched thin films of the high-temperature superconductor DyBa2Cu3O7−x with minimal defect density. A systematic set of x-ray reciprocal-space maps reveals tetragonal and orthorhombic structures with different twinning patterns and elucidates their evolution with thickness, oxygenation state, and the epitaxial relationship with the substrate. We also show that films with more pronounced orthorhombicity exhibit lower normal-state resistivities and higher superconducting transition temperatures. These findings provide guidance for the synthesis of optimized superconducting heterostructures and devices.