Dimensional crossover and band topology evolution in ultrathin semimetallic NiTe2 films

Abstract Nickel ditelluride (NiTe 2 ), a recently discovered Type-II Dirac semimetal with topological Dirac fermions near the Fermi energy, is expected to exhibit strong thickness-mediated electronic tunability and intrinsic two-gap superconductivity in the single-layer limit. Realizing such intrigu...

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Bibliographic Details
Published in:	NPJ 2D materials and applications 2021-04, Vol.5 (1), p.1-9, Article 40
Main Authors:	Hlevyack, Joseph A., Feng, Liang-Ying, Lin, Meng-Kai, Villaos, Rovi Angelo B., Liu, Ro-Ya, Chen, Peng, Li, Yao, Mo, Sung-Kwan, Chuang, Feng-Chuan, Chiang, T.-C.
Format:	Article
Language:	eng
Subjects:	electronic properties and materials Fermions Film thickness First principles MATERIALS SCIENCE Molecular beam epitaxy Single crystals spintronics Superconductivity surfaces, interfaces and thin films Thin films Topology two-dimensional materials
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Summary:	Abstract Nickel ditelluride (NiTe 2 ), a recently discovered Type-II Dirac semimetal with topological Dirac fermions near the Fermi energy, is expected to exhibit strong thickness-mediated electronic tunability and intrinsic two-gap superconductivity in the single-layer limit. Realizing such intriguing phenomena requires the fabrication of ultrathin NiTe 2 films and an understanding of the underlying physics that is still under debate. By conducting experimental band mappings of ultrathin films prepared with molecular beam epitaxy, we reveal spectroscopic evidence for the dimensionality crossover of single-crystalline ultrathin NiTe 2 films as a function of film thickness. As the film thickness increases from one to five layers, the gap in the conical topological surface states closes. Comparisons of experimental to first-principles results also highlight difficulties in fabricating atomically smooth single-layer NiTe 2 films. Our results not only provide further impetus for studying emergent phenomena in NiTe 2 but also underscore the limitations of fabricating NiTe 2 films for device applications.
ISSN:	2397-7132 2397-7132