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Magneto-optical transport in type-II Weyl semimetals in the presence of orbital magnetic moment

Panchlal Prabhat, Amit Gupta

TL;DR

The work addresses how the orbital magnetic moment (OMM) alters magneto-optical transport in gapless tilted Weyl semimetals, focusing on Type-II where the density of states is finite. It develops a semiclassical Boltzmann framework incorporating Berry curvature and OMM, deriving analytic expressions for linear and nonlinear magnetoconductivities up to quadratic in the magnetic field and for second-harmonic processes, then contrasts Type-I and Type-II behavior. A key finding is widespread suppression of many linear and nonlinear conductivities due to OMM, except for certain $\sigma_{zz}(B^2)$ contributions in Type-II which can be enhanced; chirality and tilt determine whether node pairs cancel or reinforce the net response. The results sharpen our understanding of magneto-optical experiments in tilted Weyl systems (e.g., TaAs-family, GdPtBi) and provide a framework to interpret nonlinear optical measurements influenced by Berry curvature, OMM, and tilt symmetry.

Abstract

The magneto-optical transport of gapless type-I tilted single Weyl semimetals(WSMs) exhibits suppression of total magnetoconductivities in the presence of orbital magnetic moment(OMM) in linear and nonlinear responses (Yang Gao et al., Phys. Rev. B {\bf 105}, 165307 (2022)). In this work, we extend our study to investigate magnetoconductivities in gapless type-II Weyl semimetals within the semiclassical Boltzmann approach and show the differences that arise compared to type-I Weyl semimetals.

Magneto-optical transport in type-II Weyl semimetals in the presence of orbital magnetic moment

TL;DR

The work addresses how the orbital magnetic moment (OMM) alters magneto-optical transport in gapless tilted Weyl semimetals, focusing on Type-II where the density of states is finite. It develops a semiclassical Boltzmann framework incorporating Berry curvature and OMM, deriving analytic expressions for linear and nonlinear magnetoconductivities up to quadratic in the magnetic field and for second-harmonic processes, then contrasts Type-I and Type-II behavior. A key finding is widespread suppression of many linear and nonlinear conductivities due to OMM, except for certain contributions in Type-II which can be enhanced; chirality and tilt determine whether node pairs cancel or reinforce the net response. The results sharpen our understanding of magneto-optical experiments in tilted Weyl systems (e.g., TaAs-family, GdPtBi) and provide a framework to interpret nonlinear optical measurements influenced by Berry curvature, OMM, and tilt symmetry.

Abstract

The magneto-optical transport of gapless type-I tilted single Weyl semimetals(WSMs) exhibits suppression of total magnetoconductivities in the presence of orbital magnetic moment(OMM) in linear and nonlinear responses (Yang Gao et al., Phys. Rev. B {\bf 105}, 165307 (2022)). In this work, we extend our study to investigate magnetoconductivities in gapless type-II Weyl semimetals within the semiclassical Boltzmann approach and show the differences that arise compared to type-I Weyl semimetals.
Paper Structure (14 sections, 93 equations, 15 figures)

This paper contains 14 sections, 93 equations, 15 figures.

Table of Contents

  1. Introduction
  2. Model Hamiltonian and Semiclassical Boltzmann approach
  3. Linear response of tilted WSMs
  4. Calculations of longitudinal conductivities components without magnetic field
  5. Calculations of conductivities components linear in magnetic field
  6. Calculations of quadratic-B contribution to the conductivity $\sigma_{ab}^{(B^2)}$
  7. Hall conductivities $\sigma_{ab}^{(H,0)}$ and $\sigma_{ab}^{(H,B)}$
  8. Second order non-linear response of tilted-WSMs
  9. Second harmonic conductivity $\sigma_{abc}^{0}$ in the absence of magnetic field
  10. Second harmonic conductivity $\sigma_{abc}^{B}$ in the presence of linear magnetic field
  11. The second order nonlinear Hall conductivity $\sigma_{abc}^{(H,0)}$ in the absence of magnetic field
  12. Linear B-contribution to the second order nonlinear Hall conductivity $\sigma_{abc}^{(H,B)}$
  13. Conclusion
  14. DETAILS OF THE CALCULATIONS USING SPHERICAL POLAR COORDINATES

Figures (15)

  • Figure 1: The dependence of the optical conductivity on the tilt $t_+$ at zero B field for (a) type-I WSM and(b)type-II WSM. The other parameters are taken as $\tilde{\Lambda}_k=4$,$v_F=4.13\times 10^5$ m / s, $\mu=1 meV$, and $\tau=10^{-13}s$.
  • Figure 2: The frequency dependence of optical conductivity at zero B-field for (a) type-I WSM at $t_s=0.5$ and (b) type -II WSM at $t_s=1.3$ .The other parameters are the same as those of Fig. (\ref{['fig_cond_noB_tilt']})
  • Figure 3: The dependence of the optical conductivity at B=1 on the tilt $t_+$ for (a) type-I WSM and (b)type-II WSM .The other parameters are the same as those of Fig.(\ref{['fig_cond_noB_tilt']})
  • Figure 4: The frequency dependence of optical conductivity at B = 1 T for (a) type-I WSM at $t_s=0.5$ and (b) type-II WSM at $t_s=1.3$. The other parameters are the same as those of Fig(\ref{['fig_cond_noB_tilt']})
  • Figure 5: The dependence of the optical conductivity on the tilt $t_+$ for the case of B $\parallel t_s$, for type-II WSM. The other parameters are the same as those of Fig.(\ref{['fig_cond_noB_tilt']})
  • ...and 10 more figures