Mechanical control of valley magnetization and Berry curvature dipole in monolayer MoS₂

Monolayer transition metal dichalcogenides (TMDs) are known to have the valley degree of freedom of electrons in momentum space, called K and K’. The control of valley degree of freedom utilizes the valley-dependent Berry curvatures which have the opposite signs at the K and K’ valleys. Here we report a new type of valley control using the Berry curvature dipole. By applying strain to monolayer MoS₂, we show that Berry curvature distributions about K and K’ valleys become asymmetric, leading to the emergence of the Berry curvature dipole. The Berry curvature dipole is manifested by the valley magnetization arising as functions of the Berry curvature dipole and an in-plane electric field. We fabricated several flexible monolayer MoS₂ devices and measured the valley magnetization by scanning Kerr rotation microscopy. We will discuss the dependence of the valley magnetization on the direction and magnitude of strain and in-plane electric fields. Our results obtained at room-temperature pave a way for practical valley-based electronic devices and information processing.