High-Quality Epitaxial MgB2 Josephson Junctions Grown by Molecular Beam Epitaxy

Abstract

Epitaxial MgB₂ films are grown with molecular beam epitaxy (MBE) and optimized with the assistance of in situ reflection high-energy electron diffraction (RHEED). The RHEED patterns clearly revealed the evolution of film structures with growth temperatures and Mg:B ratio, providing the most direct guidance on optimizing growth conditions. A threshold temperature is identified, below which excess Mg will physically condense into the film, and above which excess Mg vaporizes right away leading to a self-limiting growth process for chemically-bound MgB₂phases. Hetero-epitaxial (0001)-MgB₂/(111)-MgO/(0001)-MgB₂ stacks are deposited and fabricated into micro Josephson junctions, which revealed clear Fraunhofer patterns and Fiske steps, indicating superb materials quality.

© Li, L., Zhang, H., Yang, Y.-H., & Miao, G.-X. (2017). High-Quality Epitaxial MgB₂ Josephson Junctions Grown by Molecular Beam Epitaxy. Advanced Engineering Materials, 19(5), 1600792. https://doi.org/10.1002/adem.201600792