Engineering ordered arrangements of oxygen vacancies at the surface of superconducting La2CuO4 thin films

Abstract

We demonstrate how ordered arrangements of oxygen vacancies can be engineered during the growth of superconducting La2CuO4 films by oxide molecular-beam epitaxy. These arrangements are seen using in situ reflection high-energy electron diffraction. Based on qualitative real-time observations, we propose a surface reconstruction mechanism emphasizing the active role of dopants and oxygen vacancies at the film surface. Due to the specific atomic arrangement induced by dopant positions, characteristic surface “stripes” are generated, and they determine the intrinsically heterogeneous structure characterized by distorted checkerboard patterns on the surface. Not only can the surface motif during growth be monitored via characteristic surface reconstructions, but it can also be customized by altering strain, doping, and oxygen activity.

Superconductivity at Interfaces in Cuprate‐Manganite Superlattices

“…Furthermore, the ultrathin superconducting LSCO layers are sandwiched between non‐superconducting manganites, which can lead to a buckling of the CuO 2 planes. [ 29 ] In addition, the in situ RHEED pattern indicates the presence of four streaks (Figure S3, Supporting Information), [ 30 ] which depict a 5×5 super structured oxygen ordering, [ 20 ] typically associated with the presence of superconductivity in optimally doped LSCO. Our findings allow us to combine the microscopic information of sharp LSCO structures with the macroscopic evidence for a clean and optimally doped LSCO unit cell in direct proximity to an insulating phase.…”

“…To achieve high quality interfaces, we use ozone assisted molecular beam epitaxy (MBE) monitored by in situ reflection high energy electron diffraction (RHEED). [20][21][22] This method allows us to control the growth of our samples and ensure that the interfaces are of the highest quality. For a thorough structural and chemical characterization of the interfaces at the atomic scale, we utilize several scanning transmission electron microscopy (STEM) techniques, such as annular bright-field (ABF) imaging, high-angle annular dark-field (HAADF) imaging, electron energy-loss spectroscopy (EELS), and energy-loss near edge structure (ELNES) analyses.…”

Perspective: Molecular beam epitaxy of antiperovskite oxides

“…6(f), l = 4/8 streaks. These patterns are reminiscent of the 4a, 5a, and 6a superstructure streaks detected in La 2−x Sr x CuO 4 thin films and associated with ordering of oxygen vacancies [34,35]. In the case of Sr 3 SnO, future systematic studies are needed to map out the full phase diagram of surface reconstructions.…”

Advances in complex oxide quantum materials through new approaches to molecular beam epitaxy

“…By recording full videos of RHEED patterns acquired during growth and combining these with log files of growth conditions and post-growth characterization, it is in principle possible to generate sufficient data to train neural networks that could ultimately provide feedback to enable AI-driven synthesis. To date, ML and data analytics efforts have focused primarily on either interpretation of RHEED videos to extract additional information [45][46][47] or ML-assisted optimization of growth conditions, such as in SrRuO 3 [48]. These approaches take promising initial steps, but much work remains to be done in the area.…”