Bulk Fermi surfaces of the Dirac type-II semimetallic candidate <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>Ni</mml:mi><mml:msub><mml:mi>Te</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:mrow></mml:math>

Abstract

Here, we present a study on the Fermi surface of the Dirac type-II semimetallic candidate $\mathrm{Ni}{\mathrm{Te}}_{2}$ via the temperature and angular dependence of the de Haas--van Alphen (dHvA) effect measured in single crystals grown through Te flux. In contrast to its isostructural compounds like $\mathrm{Pt}{\mathrm{Se}}_{2}$, band-structure calculations predict $\mathrm{Ni}{\mathrm{Te}}_{2}$ to display a tilted Dirac node very close to its Fermi level that is located along the $\mathrm{\ensuremath{\Gamma}}$ to $A$ high-symmetry direction within its first Brillouin zone. The angular dependence of the dHvA frequencies is found to be in agreement with the first-principles calculations when the electronic bands are slightly shifted with respect to the Fermi level (${\ensuremath{\varepsilon}}_{F}$), and therefore provide support for the existence of a Dirac type-II node in $\mathrm{Ni}{\mathrm{Te}}_{2}$. Nevertheless, we observed mild disagreements between experimental observations and density functional theory (DFT) calculations as, for example, nearly isotropic and light experimental effective masses. This indicates that the dispersion of the bands is not well captured by DFT. Despite the coexistence of Dirac-like fermions with topologically trivial carriers, samples of the highest quality display an anomalous and large either linear or sublinear magnetoresistivity. This suggests that Lorentz invariance breaking Dirac-like quasiparticles dominate the carrier transport in this compound.

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