Large spin Hall conductivity and excellent hydrogen evolution reaction activity in unconventional PtTe1.75 monolayer

Abstract

Two-dimensional (2D) materials have gained lots of attention due to the potential applications. In this work, we propose that based on first-principles calculations, the (2$\times$2) patterned PtTe${}_2$ monolayer with kagome lattice formed by the well-ordered Te vacancy (PtTe${}_{1.75}$) hosts large spin Hall conductivity (SHC) and excellent hydrogen evolution reaction (HER) activity. The unconventional nature relies on the $A1@1b$ band representation (BR) of the highest valence band without SOC. The large SHC comes from the Rashba spin-orbit coupling (SOC) in the noncentrosymmetric structure induced by the Te vacancy. Even though it has a metallic SOC band structure, the ${\mathbb{Z}}_2$ invariant is well defined due to the existence of the direct band gap and is computed to be nontrivial. The calculated SHC is as large as 1.25$\times 10^3\frac{\hslash }{e}(\Omega cm{)}^{-1}$ at the Fermi level ($E_F$). By tuning the chemical potential from $E_F-0.3$ to $E_F+0.3$ eV, it varies rapidly and monotonically from $-1.2\times 10^3$ to 3.1$\times 10^3\frac{\hslash }{e}(\Omega cm{)}^{-1}$. In addition, we also find the Te vacancy in the patterned monolayer can induce excellent HER activity. Our results not only offer a new idea to search 2D materials with large SHC, i.e., by introducing inversion-symmetry breaking vacancies in large SOC systems, but also provide a feasible system with tunable SHC (by applying gate voltage) and excellent HER activity.

References in corpus (4)

• Quantum Spin Hall Effect in Ta${}_2$M${}_3$Te${}_5$ (M = Pd, Ni)
• Topological insulators in the NaCaBi family with large SOC gaps
• Twisted nodal wires and three-dimensional quantum spin Hall effect in distorted square-net compounds
• Epitaxial Growth of Monolayer PdTe2 and Patterned PtTe2 by Direct Tellurization of Pd and Pt surfaces

Cited by in corpus (5)

• Evidence for Two-dimensional Weyl Fermions in Air-Stable Monolayer PtTe${}_{1.75}$
• Majorana corner modes in unconventional monolayers of the 1T-PtSe2 family
• Unconventional phonon spectra and obstructed edge phonon modes
• Hinge Majorana Flat Band in Type-II Dirac Semimetals
• Impact of the out-of-plane conductivity on spin transport evaluation in a van der Waals material