Fermi Surface of the Weyl Type-II Metallic Candidate WP₂

Weyl type-II fermions are massless quasiparticles that obey the Weyl equation and which are predicted to occur at the boundary between electron and hole pockets in certain semimetals, i.e., the (W,Mo)(Te₁,P)₂ compounds. Here, we present a study of the Fermi surface of WP₂ via the Shubnikov-de Haas (SdH) effect. Compared to other semimetals, WP₂ exhibits a very low residual resistivity, i.e., ρ₀≃10 nΩ cm, which leads to perhaps the largest nonsaturating magnetoresistivity [ρ(H)] reported for any compound. For the samples displaying the smallest ρ₀, ρ(H) is observed to increase by a factor of 2.5×10⁷% under μ₀H=35 T at T=0.35 K. The angular dependence of the SdH frequencies is found to be in excellent agreement with the first-principles calculations when the electron and hole bands are shifted by 30 meV with respect to the Fermi level. This small discrepancy could have implications for the predicted topological character of this compound.