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Ultra-high purity elemental sources have long been considered a prerequisite for obtaining low impurity concentrations in compound semiconductors in the world of molecular beam epitaxy (MBE) since its inception in 1968. However, we demonstrate that a “dirty” solid precursor, ruthenium(III) acetylacetonate [also known as Ru(acac)3], can yield single-phase, epitaxial, and superconducting Sr2RuO4 films with the same ease and control as III-V MBE. A superconducting transition was observed at ∼0.9 K, suggesting a low defect density and a high degree of crystallinity in these films. In contrast to the conventional MBE, which employs the ultra-pure Ru metal evaporated at ∼2000 °C as a Ru source, along with reactive ozone to obtain Ru → Ru4+ oxidation, the use of the Ru(acac)3 precursor significantly simplifies the MBE process by lowering the temperature for Ru sublimation (less than 200 °C) and by eliminating the need for ozone. Combining these results with the recent developments in hybrid MBE, we argue that leveraging the precursor chemistry will be necessary to realize next-generation breakthroughs in the synthesis of atomically precise quantum materials.
Bibliographical noteFunding Information:
This work was supported by the Air Force Office of Scientific Research (AFOSR) through Grant Nos. FA9550-21-1-0025 and FA9550-21-0460 and by the NSF through the MRSEC program under Award No. DMR-2011401. Film growth was performed using instrumentation funded by AFOSR DURIP Award No. FA9550-18-1-0294. The work at the University of Washington was supported by the NSF MRSEC at UW (Grant No. DMR-1719797) and the U.S. AFOSR under Grant No. FA9550-21-1-0068 (Transport measurements) and through AFOSR DURIP Award No. FA9550-20-1-0310 (Helium 3 cryostat). Parts of this work were carried out at the Characterization Facility, University of Minnesota, which receives partial support from the NSF through the MRSEC program under Award No. DMR-2011401. Substrate preparation was carried out at the Minnesota Nano Center, which is supported by the NSF through the National Nano Coordinated Infrastructure under Award No. ECCS-2025124.
© 2023 Author(s).
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- 2 Active
9/1/20 → 8/31/26
Project: Research project