Molecular beam epitaxy and crystal structure of majority a-plane-oriented and substrate-strained Mn3Sn thin films grown directly on sapphire (0001)

The Kagome antiferromagnet Mn 3Sn has garnered much attention due to the presence of exciting properties such as anomalous Hall and Nernst effects. This paper discusses the synthesis of crystalline Mn 3Sn thin films, prepared on Al 2 O 3 (0001) substrates at 453 ± 5 °C using molecular beam epitaxy....

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Bibliographic Details
Published in:Journal of vacuum science & technology. A, Vacuum, surfaces, and films Vacuum, surfaces, and films, 2023-07, Vol.41 (4)
Main Authors: Upadhyay, Sneha, Erickson, Tyler, Hall, Hannah, Shrestha, Ashok, Ingram, David C., Sun, Kai, Moreno Hernandez, Juan Carlos, Hernandez Cocoletzi, Gregorio, Takeuchi, Noboru, Smith, Arthur R.
Format: Article
Language:English
Subjects:
CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY
Crystal structure
Electron diffraction
Epitaxy
First-principles calculations
Thin films
Transmission electron microscopy
X-ray diffraction
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Summary:The Kagome antiferromagnet Mn 3Sn has garnered much attention due to the presence of exciting properties such as anomalous Hall and Nernst effects. This paper discusses the synthesis of crystalline Mn 3Sn thin films, prepared on Al 2 O 3 (0001) substrates at 453 ± 5 °C using molecular beam epitaxy. The growth is monitored in situ using reflection high energy electron diffraction and measured ex situ using x-ray diffraction, Rutherford back-scattering, and cross-sectional scanning transmission electron microscopy. Our analysis shows the in-plane lattice constants of a 1 , M = 4.117 ± 0.027 Å and a 2 , M = 4.943 ± 0.033 Å, which is a very unexpected result when compared to the bulk a-plane Mn 3Sn. This indicates a strain in the film and makes it challenging to provide a straightforward explanation. In an effort to explain our results, we discuss two possible orientation relationships between the Mn 3Sn films and the sapphire substrates. Samples prepared under these conditions appear to have smooth surfaces locally, but overall the film has a 3D island morphology. First-principles calculations provide atomic models of the Mn 3Sn (11 2 ¯0) lattice on Al 2 O 3 (0001) high symmetry sites, indicating that the L3-R90 ° is the most stable configuration. A detailed discussion of the experimental data and theoretical results, as well as strain effects, is provided.
ISSN:0734-2101
1520-8559
DOI:10.1116/6.0002535