Time-resolved Hall conductivity of pulse-driven topological quantum systems

LUCILA PERALTA GAVENSKY; GONZALO USAJ; CARLOS A. BALSEIRO

PHYSICAL REVIEW B

AMER PHYSICAL SOC

Lugar: New York; Año: 2018 vol. 98 p. 165414 - 165414

1098-0121

We address the question of how the time-resolved bulk Hall response of a two-dimensional honeycomb lattice when driving the system with a pulsed perturbation. A simple toy model that switches a valley Hall by breaking inversion symmetry is studied in detail for slow quasiadiabatic ramps and sudden quenches, an oscillating dynamical response that depends strongly on doping and time-averaged values that determined both by the out of equilibrium occupations and the Berry curvature of the final states. On the hand, the effect of irradiating the sample with a circularly-polarized pump pulse that breaks time reversal and thus ramps the system into a nontrivial topological regime is probed. Even though there is a average signal due to the breakdown of the Floquet adiabatical picture, some features of the photon- topological bands are revealed to be present even in a few femtosecond timescale. Small frequency during the transient response evidence the emergence of dynamical Floquet gaps which are consistent the instantaneous amplitude of the pump envelope. On the other hand, a characteristic heterodyning effect manifested in the model. The presence of a remnant Hall response for ultrashort pulses that contain only a few of the radiation field is briefly discussed.