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Condensed Matter > Mesoscale and Nanoscale Physics

Title: Valley Hall Transport of Photon-Dressed Quasiparticles in 2D Dirac Semiconductors

Abstract: We present a theory of the photovoltaic valley-dependent Hall effect in a two-dimensional 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. The non-perturbative renormalization effect of the pump field manifests itself in the dynamics of the photon-dressed quasiparticles, with a quasienergy spectrum characterized by dynamical gaps $\delta_\eta$ ($\eta$ is the valley index) that strongly depend on field amplitude and polarization. Non-equilibrium carrier distribution functions are determined by the pump field frequency $\omega$ as well as the ratio of intraband relaxation time $\tau$ and interband recombination time $\tau_{\mathrm{rec}}$. We obtain analytic results in three regimes, when (I) all relaxation processes are negligible, (II) $\tau \ll \tau_{\mathrm{rec}}$, and (III) $\tau \gg \tau_{\mathrm{rec}}$, and display corresponding asymptotic dependences on $\delta_\eta$ and $\omega$. We then apply our theory to two-dimensional 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.
Comments: 6 pages, 4 figures
Subjects: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Cite as: arXiv:1803.06607 [cond-mat.mes-hall]
  (or arXiv:1803.06607v1 [cond-mat.mes-hall] for this version)

Submission history

From: Wang-Kong Tse [view email]
[v1] Sun, 18 Mar 2018 05:47:52 GMT (377kb,D)