Detection of hole pockets in type-II Weyl semimetal MoTe₂ from Shubnikov-de Haas quantum oscillations

The bulk electronic structure of T_d-MoTe₂ features large hole Fermi pockets at the Brillouin zone center (Γ) and two electron Fermi surfaces along the Γ-X direction. However, the large hole pockets, whose existence has important implications for the Weyl physics of T_d-MoTe₂, had never been conclusively detected in quantum oscillations. In this presentation, we report an unambiguous detection of these elusive hole pockets via Shubnikov-de Haas (SdH) quantum oscillations. At ambient pressure, the quantum oscillation frequencies for these pockets are 988 T and 1513 T, when the magnetic field is applied along the c-axis. The quasiparticle effective masses m* associated with these frequencies are 1.50 m_e and 2.77 m_e, respectively, indicating the importance of Coulomb interactions in this system. We further measure the SdH oscillations under pressure. At 13 kbar, we detected a peak at 1798~T with m* = 2.86 m_e. Relative to the oscillation data at a lower pressure, the amplitude of this peak experienced an enhancement, which can be attributed to the reduced curvature of the hole pockets under pressure. Combining with DFT + U calculations, our data shed light on why these important hole pockets had not been detected until now.