Ultrafast currents in the monolayer of transition metal dichalcogenides

We theoretically predict that in a monolayer of the transition metal dichalcogenide (TMDCs), an applied ultrafast intense optical pulse with the polarization perpendicular to the TMDC’s axis of symmetry induces two types of currents: a trivial current, which flows in the direction of the applied pulse and a nontrivial current, which flows in the direction perpendicular to the polarization of the pulse. The applied pulse has a linear polarization with a high amplitude of several Volt per Angstrom and the duration of a few femtoseconds. Our results show that the ultrafast field-driven currents with asymmetric profiles transfer the electrons asymmetrically, which causes the monolayer of TMDC to become electrically polarized. The induced nontrivial current and the net electrical polarization are due to Berry curvature, which is nonzero near the K and K’ valleys [1].
[1]: S. Azar Oliaei Motlagh, Jhih-Sheng Wu, Vadym Apalkov, and Mark I. Stockman
Phys. Rev. B 98, 081406(R)2018.