Spin Polarized Hole Transport in Monolayer WSe₂ Quantum Structures

Challenges associated with low carrier mobility and the quality of electrical contacts in semiconducting transition metal dichalcogenides (TMDs) have hampered the progress of transport studies, especially at low temperature and low carrier density.

Here, we first present a device structure for achieving high mobility and low resistive ohmic contacts that relies on the independent tunability of the carrier density in the contact region. We demonstrate that low resistive ohmic contacts survive at temperatures as low as 10 mK and can successfully be used in hole transport measurements to probe the low carrier density regime in monolayer tungsten diselenide (WSe₂).

We then report magneto-transport measurements performed in a perpendicular magnetic field up to 8 T. We discuss the appearance of a Landau fan diagram in which we observe fully spin polarized hole transport at low filling factors down to ν = 1. Finally, we discuss the behavior of the Landau fan diagram at higher densities, where we observe an unconventional alternating visibility pattern corresponding to the alternating population of the K and K’ valleys as the density is swept.