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arXiv · 1908.04099

Low-energy type-II Dirac fermions and spin-polarized topological surface states in transition-metal dichalcogenide NiTe$_2$

Barun Ghosh·Debashis Mondal·Chia-Nung Kuo·Chin Shan Lue·Jayita Nayak·Jun Fujii·Ivana Vobornik·Antonio Politano·Amit Agarwal
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Abstract

Using spin- and angle- resolved photoemission spectroscopy (spin-ARPES) together with ${\it ab~initio}$ calculations, we demonstrate the existence of a type-II Dirac semimetal state in NiTe$_2$. We show that, unlike PtTe$_2$, PtSe$_2$, and PdTe$_2$, the Dirac node in NiTe$_2$ is located in close vicinity of the Fermi energy. Additionally, NiTe$_2$ also hosts a pair of band inversions below the Fermi level along the $Γ-A$ high-symmetry direction, with one of them leading to a Dirac cone in the surface states. The bulk Dirac nodes and the ladder of band inversions in NiTe$_2$ support unique topological surface states with chiral spin texture over a wide range of energies. Our work paves the way for the exploitation of the low-energy type-II Dirac fermions in NiTe$_2$ in the fields of spintronics, THz plasmonics and ultrafast optoelectronics.

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Barun Ghosh, Debashis Mondal, Chia-Nung Kuo, Chin Shan Lue, Jayita Nayak, Jun Fujii, Ivana Vobornik, Antonio Politano, Amit Agarwal. 2019-08-13. Low-energy type-II Dirac fermions and spin-polarized topological surface states in transition-metal dichalcogenide NiTe$_2$. https://doi.org/10.1103/physrevb.100.195134

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