2018/01/30 by Soumya Mukherjee, S. P. Mukherjee, J. P. Carbotte +1 · 3 citations
Materials Science · Physics and Astronomy · #Band gap #Condensed matter physics #Graphene research and applications #Omega #Physics #Quantum Mechanics and Non-Hermitian Physics #Quantum mechanics #Semimetal #Topological Materials and Phenomena #Weyl semimetal #cond-mat.str-el
paper · pdf · doi:10.1103/physrevb.97.045150
published as Phys. Rev. B 97, 045150 (2018) · 14 pages, minor corrections in the published version
openalex publication_date 2018/01/30 · arxiv created 2018/03/16 · arxiv updated 2018/03/28 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We calculate the absorptive part of the ac optical conductivity of a multi-Weyl semimetal with winding number J in both the direction of the tilt \ensuremathσzz(\mathrm\ensuremathΩ) and perpendicular to it \ensuremathσxx(\mathrm\ensuremathΩ) as a function of photon energy \mathrm\ensuremathΩ, tilt C, and chemical potential \ensuremathμ (doping). For zero tilt there is a discontinuous rise in the conductivity at twice the value of the chemical potential \mathrm\ensuremathΩ=2\ensuremathμ. Below 2\ensuremathμ, both \ensuremathσxx(\mathrm\ensuremathΩ) and \ensuremathσzz(\mathrm\ensuremathΩ) are zero and above 2\ensuremathμ they merge with their value at charge neutrality and display a linear in \mathrm\ensuremathΩ dependence for J=1 while for J=2, \ensuremathσxx(\mathrm\ensuremathΩ) remains linear but \ensuremathσzz(\mathrm\ensuremathΩ) is instead constant. For finite tilt the sharp jump at \mathrm\ensuremathΩ=2\ensuremathμ is lost and the onset of absorption starts instead from zero at a lower photon energy \mathrm\ensuremathΩ=2\ensuremathμ/(1+C) after which it acquires a quasilinear rise to merge with the undoped untilted interband background at \mathrm\ensuremathΩ=2\ensuremathμ/(1\ensuremath-C) for type I Weyl while for type II the undoped untilted background is never recovered. For noncentrosymmetric materials the energies of a pair of opposite chirality Weyl nodes become shifted by \ifmmode±\else\textpm\fiQ0 and this leads to two separate absorption edges corresponding to the effective chemical potential of each of the two nodes at 2(\ensuremathμ+\ensuremathχQ0) depending on chirality \ensuremathχ=\ifmmode±\else\textpm\fi. We provide analytic expressions for the conductivity in this case which depend only on the ratio Q0/\ensuremathμ and tilt when plotted against \mathrm\ensuremathΩ/\ensuremathμ. The signature of finite energy shift Q0 is more pronounced for \ensuremathσzz and J=2 than for the other cases.