Photoinduced quantum spin and valley Hall effects, and orbital magnetization in monolayer ${\mathrm{MoS}}_2$

We theoretically demonstrate that 100% valley-polarized transport in monolayers of ${\mathrm{MoS}}_2$ and other group-VI dichalcogenides can be obtained using off-resonant circularly polarized light. By tuning the intensity of the off-resonant light the intrinsic band gap in one valley is reduced, while it is enhanced in the other valley, enabling single valley quantum transport. As a consequence, we predict (i) enhancement of the longitudinal electrical conductivity, accompanied by an increase in the spin polarization of the flowing electrons, (ii) enhancement of the intrinsic spin Hall effect, together with a reduction of the intrinsic valley Hall effect, and (iii) enhancement of the orbital magnetic moment and orbital magnetization. These mechanisms provide appealing opportunities to the design of nanoelectronics based on dichalcogenides.

Figure 1

Brillouin zone of monolayer ${\mathrm{MoS}}_2$ and schematic electronic structure in the presence of off-resonant light and absence of intrinsic SOC.

Figure 2

Band structure of monolayer ${\mathrm{MoS}}_2$ in the presence of both off-resonant light and intrinsic SOC for the (top) $K$ and (bottom) $K^{\prime }$ valley.