Hall and thermoelectric measurement of Type-II Weyl semimetal TaIrTe₄

Weyl semimetal has gapless band structures protected by topology and symmetry which possess many interesting properties, like Fermi arc surface states, chiral anomaly etc. Without the constraint from the Lorentz invariance, type-II Weyl semimetal has a tilted Weyl cone that electron and hole pockets exist at the node energy. TaIrTe₄ is theoretically predicted to be a type-II Weyl semimetal hosting four well-separated Weyl points which is the minimum required by the symmetry. Here, we present our study of TaIrTe₄ with Hall and thermoelectric measurement. In the Hall measurement, two pairs of electron-hole pockets with quite different mobility could be identified by fitting the Hall curves. The temperature dependence of the carrier density shows an obvious movement of the Fermi level which is quite similar to the reported temperature-induced Lifshitz transition in WTe₂. The Hall result suggests that hole-type carrier dominate the transport properties which is in the opposite to the negative Seebeck coefficient. The Nernst coefficient has the same temperature dependence as the mobility of the dominate hole band.