Electron-hole compensation effect between topologically trivial electrons and nontrivial holes in NbAs
Abstract
Via angular Shubnikov-de Hass (SdH) quantum oscillations measurements, we determine the Fermi surface topology of NbAs, a Weyl semimetal candidate. The SdH oscillations consist of two frequencies, corresponding to two Fermi surface extrema: 20.8 T (α-pocket) and 15.6 T (β-pocket). The analysis, including a Landau fan plot, shows that the β-pocket has a Berry phase of π and a small effective mass 0.033 m0, indicative of a nontrivial topology in momentum space; whereas the α-pocket has a trivial Berry phase of 0 and a heavier effective mass 0.066 m0. From the effective mass and the β-pocket frequency we determine that the Weyl node is 110.5 meV from the chemical potential. A novel electron-hole compensation effect is discussed in this system, and its impact on magneto-transport properties is addressed. The difference between NbAs and other monopnictide Weyl semimetals is also discussed.