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A simple electron counting model for half-Heusler surfaces

Kawasaki, Jason K.; Sharan, Abhishek; Johansson, Linda I. M.; Hjort, Martin LU ; Timm, Rainer LU ; Thiagarajan, Balasubramanian LU ; Schultz, Brian D.; Mikkelsen, Anders LU ; Janotti, Anderson and Palmstrøm, Chris J. (2018) In Science Advances 4.
Abstract
Heusler compounds are a ripe platform for discovery and manipulation of emergent properties in topological and magnetic heterostructures. In these applications, the surfaces and interfaces are critical to performance; however, little is known about the atomic-scale structure of Heusler surfaces and interfaces or why they reconstruct. Using a combination of molecular beam epitaxy, core-level and angle-resolved photoemission, scanning tunneling microscopy, and density functional theory, we map the phase diagram and determine the atomic and electronic structures for several surface reconstructions of CoTiSb (001), a prototypical semiconducting half-Heusler. At low Sb coverage, the surface is characterized by Sb-Sb dimers and Ti vacancies,... (More)
Heusler compounds are a ripe platform for discovery and manipulation of emergent properties in topological and magnetic heterostructures. In these applications, the surfaces and interfaces are critical to performance; however, little is known about the atomic-scale structure of Heusler surfaces and interfaces or why they reconstruct. Using a combination of molecular beam epitaxy, core-level and angle-resolved photoemission, scanning tunneling microscopy, and density functional theory, we map the phase diagram and determine the atomic and electronic structures for several surface reconstructions of CoTiSb (001), a prototypical semiconducting half-Heusler. At low Sb coverage, the surface is characterized by Sb-Sb dimers and Ti vacancies, while, at high Sb coverage, an adlayer of Sb forms. The driving forces for reconstruction are charge neutrality and minimizing the number of Sb dangling bonds, which form metallic surface states within the bulk bandgap. We develop a simple electron counting model that explains the atomic and electronic structure, as benchmarked against experiments and first-principles calculations. We then apply the model to explain previous experimental observations at other
half-Heusler surfaces, including the topological semimetal PtLuSb and the half-metallic ferromagnet NiMnSb. The model provides a simple framework for understanding and predicting the surface structure and properties
of these novel quantum materials. (Less)
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author
organization
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type
Contribution to journal
publication status
published
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in
Science Advances
volume
4
publisher
American Association for the Advancement of Science (AAAS)
external identifiers
  • scopus:85048280098
ISSN
2375-2548
DOI
10.1126/sciadv.aar5832
language
English
LU publication?
yes
id
5b9e0181-309a-4aae-9d28-5c64c12e660a
date added to LUP
2018-08-15 16:52:07
date last changed
2018-10-28 04:54:35
@article{5b9e0181-309a-4aae-9d28-5c64c12e660a,
  abstract     = {Heusler compounds are a ripe platform for discovery and manipulation of emergent properties in topological and magnetic heterostructures. In these applications, the surfaces and interfaces are critical to performance; however, little is known about the atomic-scale structure of Heusler surfaces and interfaces or why they reconstruct. Using a combination of molecular beam epitaxy, core-level and angle-resolved photoemission, scanning tunneling microscopy, and density functional theory, we map the phase diagram and determine the atomic and electronic structures for several surface reconstructions of CoTiSb (001), a prototypical semiconducting half-Heusler. At low Sb coverage, the surface is characterized by Sb-Sb dimers and Ti vacancies, while, at high Sb coverage, an adlayer of Sb forms. The driving forces for reconstruction are charge neutrality and minimizing the number of Sb dangling bonds, which form metallic surface states within the bulk bandgap. We develop a simple electron counting model that explains the atomic and electronic structure, as benchmarked against experiments and first-principles calculations. We then apply the model to explain previous experimental observations at other<br/>half-Heusler surfaces, including the topological semimetal PtLuSb and the half-metallic ferromagnet NiMnSb. The model provides a simple framework for understanding and predicting the surface structure and properties<br/>of these novel quantum materials. },
  author       = {Kawasaki, Jason K. and Sharan, Abhishek and Johansson, Linda I. M. and Hjort, Martin and Timm, Rainer and Thiagarajan, Balasubramanian and Schultz, Brian D. and Mikkelsen, Anders and Janotti, Anderson and Palmstrøm, Chris J.},
  issn         = {2375-2548},
  language     = {eng},
  month        = {06},
  publisher    = {American Association for the Advancement of Science (AAAS)},
  series       = {Science Advances},
  title        = {A simple electron counting model for half-Heusler surfaces},
  url          = {http://dx.doi.org/10.1126/sciadv.aar5832},
  volume       = {4},
  year         = {2018},
}