Valley Hall transport of photon-dressed quasiparticles in two-dimensional Dirac semiconductors

• Published in: New journal of physics 2018-08, Vol.20 (8), p.83007
• Main Authors: Kovalev, V M, Tse, Wang-Kong, Fistul, M V, Savenko, I G
• Format: Article
• Language: English
• Subjects: Distribution functions; Electromagnetic fields; Hall effect; photon-dressed quasiparticles; Photons; Physics; Relaxation time; Transition metal compounds; transition-metal dichalcogenides; Transport; two-dimensional materials; Valence band; valley Hall effect
• ISSN: 1367-2630; 1367-2630
• DOI: 10.1088/1367-2630/aad5f8

We present a theory of the photovoltaic valley-dependent Hall effect in a two-dimensional (2D) Dirac semiconductor subject to an intense near-resonant electromagnetic field. Our theory captures and elucidates the influence of both the field-induced resonant interband transitions and the nonequilibrium carrier kinetics on the resulting valley Hall transport in terms of photon-dressed quasiparticles (PDQs). The non-perturbative renormalization effect of the pump field manifests itself in the dynamics of the PDQs, with a quasienergy spectrum characterized by dynamical gaps δ ( is the valley index) that strongly depend on field amplitude and polarization. Nonequilibrium carrier distribution functions are determined by the pump field frequency as well as the ratio of intraband relaxation time τ and interband recombination time τrec. We obtain analytic results in three regimes, when (I) all relaxation processes are negligible, (II) τ < τrec, and (III) τ > τrec, and display corresponding asymptotic dependences on δ and . We then apply our theory to 2D transition-metal dichalcogenides, and find a strong enhancement of valley-dependent Hall conductivity as the pump field frequency approaches the transition energies between the pair of spin-resolved conduction and valence bands at the two valleys.