Kitkaite NiTeSe, an Ambient-Stable Layered Dirac Semimetal with Low-Energy Type-II Fermions with Application Capabilities in Spintronics and Optoelectronics

Here, it is shown that kitkaite (NiTeSe) represents an ideal platform for type-II Dirac fermiology based on spin-resolved angle-resolved photoemission spectroscopy and density functional theory. Precisely, the existence of type-II bulk Dirac fermions is discovered in NiTeSe around the Fermi level together with the presence of topological strongly spin polarized surface states.
I. Vobornik et al., Adv. Funct. Mater. 31, 2106101 (2021)

Here, by means of spin-polarized angle-resolved photoemission spectroscopy (spin-ARPES) and density functional theory (DFT), we demonstrate the existence of type-II bulk Dirac fermions in NiTeSe, with the energy of the Dirac point slightly below the Fermi level (ED = −0.23 eV). Additionally, our surface-science investigations in near-ambient pressure conditions demonstrate the ambient stability of the NiTeSe surface. These findings make NiTeSe an excellent candidate for technological applications without the need for any encapsulation procedure. To validate NiTeSe-based optoelectronic applications, we fabricated an ambient-stable NiTeSe photodetector with an ultrafast response by integrating only a bow-tie-type antenna under millimeter-wave illumination. Definitely, the NiTeSe-based device exhibited improved performance compared to similar ones based on graphene, black phosphorus, topological insulators, and van der Waals semiconductors.

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