Gate-Defined One-Dimensional Channel and Broken Symmetry States in MoS${}_2$ van der Waals Heterostructures

We have realized encapsulated trilayer MoS${}_2$ devices with gated graphene contacts. In the bulk, we observe an electron mobility as high as 7000~cm${}^2$/(V s) at a density of 3 $\times$ 10${}^{12}$~cm${}^{-2}$ at a temperature of 1.9~K. Shubnikov–de Haas oscillations start at magnetic fields as low as 0.9~T. The observed 3-fold Landau level degeneracy can be understood based on the valley Zeeman effect. Negatively biased split gate electrodes allow us to form a channel that can be completely pinched off for sufficiently large gate voltages. The measured conductance displays plateau-like features.