Elastic and transport properties of topological semimetal ZrTe

Abstract

Topological semimetals may have substantial applications in electronics, spintronics, and quantum computation. Recently, ZrTe was predicted as a new type of topological semimetal due to the coexistence of Weyl fermions and massless triply degenerate nodal points. In this work, the elastic and transport properties of ZrTe are investigated by combining the first-principles calculations and semiclassical Boltzmann transport theory. Calculated elastic constants prove the mechanical stability of ZrTe, and the bulk modulus, shear modulus, Young’s modulus, and Poisson’s ratio also are calculated. It is found that spin–orbit coupling (SOC) has slightly enhanced effects on the Seebeck coefficient, which along the a(b) and c directions for pristine ZrTe at 300 K is 46.26 μ VK ^−1 and 80.20 μ VK ^−1 , respectively. By comparing the experimental electrical conductivity of ZrTe (300 K) with the calculated value, the scattering time is determined as 1.59 × 10 ^−14 s. The predicted room-temperature electronic thermal conductivity along the a(b) and c directions is 2.37 ${\mathrm{Wm}}^{-1}{{\rm{K}}}^{-1}$ and 2.90 ${\mathrm{Wm}}^{-1}{{\rm{K}}}^{-1}$ , respectively. The room-temperature lattice thermal conductivity is predicted as 17.56 ${\mathrm{Wm}}^{-1}{{\rm{K}}}^{-1}$ and 43.08 ${\mathrm{Wm}}^{-1}{{\rm{K}}}^{-1}$ along the a(b) and c directions, showing very strong anisotropy. Calculated results show that isotope scattering produces an observable effect on lattice thermal conductivity. To observably reduce lattice thermal conductivity by nanostructures, the characteristic length should be smaller than 70 nm, based on cumulative lattice thermal conductivity with respect to the phonon mean free path (MFP) at 300 K. It is noted that the average room-temperature lattice thermal conductivity of ZrTe is slightly higher than that of isostructural MoP, which is due to larger phonon lifetimes and smaller Grüneisen parameters. Finally, the total thermal conductivity as a function of temperature is predicted for pristine ZrTe. Our works provide valuable information for ZrTe-based nano-electronics devices, and motivate further experimental works to study elastic and transport properties of ZrTe.

Keywords

• elastic constants
• Seebeck coefficient
• lattice thermal conductivity
• 72.15.Jf
• 71.20.-b
• 71.70.Ej