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

doi:10.1103/PhysRevB.100.195134

paper

Low-energy type-II Dirac fermions and spin-polarized topological surface states in transition-metal dichalcogenide NiTe $_{2}$

arXiv:1908.04099 · doi:10.1103/PhysRevB.100.195134

Abstract

Using spin- and angle- resolved photoemission spectroscopy (spin-ARPES) together with $ab initio$ 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.

4+ pages and 4 figures; minor revision

Low-energy type-II Dirac fermions and spin-polarized topological surface states in transition-metal dichalcogenide NiTe2​

Abstract

Low-energy type-II Dirac fermions and spin-polarized topological surface states in transition-metal dichalcogenide NiTe $_{2}$