Quantized conductance 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$^{2}$/Vs at a density of 3 $\times$ 10$^{12}$ cm$^{-2}$ at a temperature of 1.5 K. Shubnikov-de Haas oscillations start at magnetic fields as low as 1 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 which can be completely pinched off for sufficiently large gate voltages. Plateau-like features occur at conductance values consistent with the expected degeneracies at zero and finite magnetic fields.