Quantum Oscillations, Thermoelectric Coefficients, and the Fermi Surface of Semimetallic WTe2

We present a study of angle-resolved quantum oscillations of electric and thermoelectric transport coefficients in semimetallic WTe₂, which has the particularity of displaying a large B² magnetoresistance. The Fermi surface consists of two pairs of electronlike and holelike pockets of equal volumes in a "Russian doll" structure. The carrier density, Fermi energy, mobility, and the mean-free path of the system are quantified. An additional frequency is observed above a threshold field and attributed to the magnetic breakdown across two orbits. In contrast to all other dilute metals, the Nernst signal remains linear in the magnetic field even in the high-field (ω_cτ ≫1 ) regime. Surprisingly, none of the pockets extend across the c axis of the first Brillouin zone, making the system a three-dimensional metal with moderate anisotropy in Fermi velocity, yet a large anisotropy in the mean-free path.