Band topology and non-trivial surface States in type-II Dirac semi-metal (Ni, Pd)Te2

TL;DR

This study investigates the topological electronic properties of NiTe2 and PdTe2, revealing strong topological surface states and Dirac fermions in PdTe2 through first-principles calculations.

Contribution

The paper provides a detailed first-principles analysis of the topological states in NiTe2 and PdTe2, including the calculation of Z2 invariants and surface states, highlighting the presence of Dirac cones in PdTe2.

Findings

PdTe2 exhibits Dirac cone surface states.

NiTe2 shows strong topological properties but no clear Dirac cone.

Both materials have non-trivial topological classifications.

Abstract

The semi-metals having electrons near the Fermi level follow the relativistic equation of motion, and show Dirac or Weyl-type behavior. Their orbital resolved electronic bands analysis indicates the non-trivial topological states. Through the first principle methods, the electronic band structure of bulk and thin layers of transition metal dichalcogenides NiTe2 and PdTe2 are calculated and analyzed. Implementation of Hubbard corrections to the band structure indicates zero magnetization, though atoms of Ni are magnetic. Z2 invariant index is calculated for topological classification for both materials and is found to possess strong topology indicating robust topological surface states. Further, Fermi surfaces and topological surface states are computed into kz plane showing the presence of Dirac-fermions by forming of Dirac cone for PdTe2 but for NiTe2 we do not get clear evidence.