Fermi-crossing Type-II Dirac fermions and topological surface states in NiTe2

TL;DR

This paper reports that NiTe2 hosts Type-II Dirac fermions and topological surface states near the Fermi level, making it promising for spintronics applications due to its unique electronic structure.

Contribution

It demonstrates that NiTe2 uniquely combines bulk Type-II Dirac points and topological surface states close to the Fermi level, driven by Ni d orbital contributions.

Findings

Type-II Dirac points near Fermi level in NiTe2

Topological surface states intersect Fermi energy

Large spin splitting of 120 meV in surface states

Abstract

Transition-metal dichalcogenides (TMDs) offer an ideal platform to experimentally realize Dirac fermions. However, typically these exotic quasiparticles are located far away from the Fermi level, limiting the contribution of Dirac-like carriers to the transport properties. Here we show that NiTe2 hosts both bulk Type-II Dirac points and topological surface states. The underlying mechanism is shared with other TMDs and based on the generic topological character of the Te p-orbital manifold. However, unique to NiTe2, a significant contribution of Ni d orbital states shifts the energy of the Type-II Dirac point close to the Fermi level. In addition, one of the topological surface states intersects the Fermi energy and exhibits a remarkably large spin splitting of 120 meV. Our results establish NiTe2 as an exciting candidate for next-generation spintronics devices.