Fermi-crossing Type-II Dirac fermions and topological surface states in NiTe2
Saumya Mukherjee, Sung Won Jung, Sophie F. Weber, Chunqiang Xu, Dong Qian, Xiaofeng Xu, Pabitra Kumar Biswas⃰, T. K. Kim, L. C. Chapon, Matthew D. Watson, Jeffrey B. Neaton, Céphise Cacho
Abstract
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 NiTe 2 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 NiTe 2 , 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 NiTe 2 as an exciting candidate for next-generation spintronics devices.