Shubnikov-de Haas Oscillations in bilayer MoSe₂: effective mass and carrier density dependent quantum Hall states sequence

We report magnetotransport studies of high-mobility electrons in dual-gated bilayer MoSe₂ Hall-bars. Samples are fabricated using dry-transfer techniques, where an exfoliated MoSe₂ bilayer is encapsulated in hexagonal boron-nitride dielectrics. The introduction of metal bottom-contacts coupled with electrostatic doping of the contact regions yields low-resistance n-type contacts down to low temperatures (0.3 K). The measured longitudinal resistance shows clear Shubnikov-de Haas (SdH) oscillations, and quantum Hall states (QHSs) developing at high magnetic fields. The temperature dependence of the SdH oscillations amplitude allows to extract an electron effective mass of 0.8m_e. The QHSs sequence shows transitions from even to odd filling factors as a function of electron density, which indicate the Zeeman to cyclotron energy ratio changes with density, likely because of electron-electron interaction. The QHSs are insensitive to an applied in-plane magnetic field, which suggest the electron spins are locked perpendicular to the MoSe₂ plane because of strong spin-orbit interaction.