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Research Article

Obtaining tetragonal FeAs layer and superconducting KxFe2As2 by molecular beam epitaxy

Cui Ding1,2, Yuanzhao Li1, Shuaihua Ji1, Ke He1, Lili Wang1,3(), Qi-Kun Xue1,2,4()
State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
Beijing Academy of Quantum Information Sciences, Beijing 100193, China
Collaborative Innovation Center of Quantum Matter, Beijing 100084, China
Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
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We fabricate the tetragonal FeAs by the topotactic reaction of multilayer FeTe films with arsenic and then obtain KxFe2As2 upon potassium intercalation. We demonstrate characteristic 2×2 reconstruction on the FeAs layer and the emergence of superconductivity with an onset Tc of 10 K in KxFe2As2/FeTe, higher than the value of bulk KFe2As2.

Abstract

Atomic characterization on tetragonal FeAs layer and engineering FeAs superlattices is highly desirable to get deep insight into the multi-band superconductivity in iron-pnictides. We fabricate the tetragonal FeAs layer by topotactic reaction of FeTe films with arsenic and then obtain KxFe2As2 upon potassium intercalation using molecular beam epitaxy. The in-situ low-temperature scanning tunneling microscopy/spectroscopy investigations demonstrate characteristic 2×2 reconstruction of the FeAs layer and stripe pattern of KxFe2As2, accompanied by the development of a superconducting-like gap. The ex-situ transport measurement with FeTe capping layers shows a superconducting transition with an onset temperature of 10 K. This work provides a promising way to characterize the FeAs layer directly and explore rich emergent physics with epitaxial superlattice design.

Keywords

tetragonal FeAsKxFe2As2interface enhanced superconductivitytopotactic reactionmolecular beam epitaxy

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Nano Research
Volume 16 Issue 2,
February 2023
Pages 3040-3045
DOI: 10.1007/s12274-022-4956-4
Cite this article:
Ding C, Li Y, Ji S, et al. Obtaining tetragonal FeAs layer and superconducting KxFe2As2 by molecular beam epitaxy. Nano Research, 2023, 16(2): 3040-3045. https://doi.org/10.1007/s12274-022-4956-4
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Epitaxial growthFilm growthMonolayersScanning tunneling microscopyScanning tunneling microscopy
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