Nonlinear exciton drift in piezoelectric two-dimensional materials

The noncentrosymmetric nature of single-layer (SL) transition-metal dichalcogenides (TMD) manifests itself in the finite piezoelectricity and valley-Zeeman coupling. We microscopically model nonlinear exciton transport nanobubbles SL TMDs. Thanks to giant piezoelectric effect, we obtain an enormous internal electric field, ${E}_{\mathrm{piezo}}\ensuremath{\sim}{10}^{7}\phantom{\rule{0.16em}{0ex}}\mathrm{V}/\mathrm{m}$, resulting a built-in dipole moment excitons. demonstrate that piezo-induced dipole-dipole interaction provides novel channel for distinct from conventional isotropic funneling excitons leads formation hexagon-shaped droplet on top circularly symmetric nanobubbles. Moreover, found hexagonal distribution density is preserved even strongly elliptic effect tunable via bubble-size dependence field ${E}_{\mathrm{piezo}}\ensuremath{\sim}{h}_{\mathrm{max}}^{2}/{R}^{3}$ with ${h}_{\mathrm{max}}$ $R$ being bubble height radius, respectively.