Circular Photocurrent in Weyl Semimetals with Mirror Symmetry

• Published in: Journal of experimental and theoretical physics Vol. 129; no. 1; pp. 139 - 146
• Main Authors: Leppenen, N. V., Ivchenko, E. L., Golub, L. E.
• Format: Journal Article
• Language: English
• Published: Moscow Pleiades Publishing 01.07.2019; Springer; Springer Nature B.V
• Subjects: ABSORPTION; ANTIMONY COMPOUNDS; ARSENIC COMPOUNDS; BISMUTH COMPOUNDS; CHIRALITY; Circular polarization; Classical and Quantum Gravitation; CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; Dispersion curve analysis; Electromagnetic absorption; Electronic Properties of Solid; Elementary Particles; ENERGY SPECTRA; HAMILTONIANS; Metalloids; NIOBIUM COMPOUNDS; Particle and Nuclear Physics; PHOSPHORUS COMPOUNDS; PHOTOCURRENTS; Photoelectric effect; Photoelectric emission; Physics; Physics and Astronomy; POLARIZATION; Quantum Field Theory; REFLECTION; Relativity Theory; SEMIMETALS; Solid State Physics; Symmetry; SYMMETRY GROUPS; TANTALUM COMPOUNDS; Tensors; Transition metals; Valleys
• ISSN: 1063-7761; 1090-6509
• DOI: 10.1134/S1063776119070070

We have considered theoretically Weyl’s semimetals, for which the point symmetry group contains reflection planes and which have equivalent valleys with opposite chiralities. These materials include the most often studied compounds, viz., monopnictides TaAs, NbAs, TaP, NbP of transition metals, as well as Bi 1 ‒   x Sb x alloys. Circular photogalvanic current inverting its direction upon the sign reversal of the circular polarization has been calculated for light absorption under direct optical transitions near Weyl points. The total contribution of all valleys to the photocurrent differs from zero beyond the limits of Weyl’s model when the spin-independent tilt linear in wavevector k or spin-dependent terms cubic in k are taken into account additionally in the effective electron Hamiltonian. When the tilt of the energy dispersion curve in a Weyl semimetal of symmetry is considered, the photogalvanic current can be expressed in terms of the components of rank-two symmetric tensor determining the energy spectrum of carriers near a Weyl’s node. At low temperatures, this contribution to the photocurrent is excited in a certain limited frequency interval Δ. The photocurrent associated with cubic corrections in the optical absorption region is proportional to the square of light frequency and is generated both within window Δ and beyond its limits.