Emergent Weyl fermions in WTe2 probed with Electron-States-Resolved NMR crystallography

Weyl semimetals (WSM) are a new quantum state of matter hosting the condensed matter physics analogue of the massless Weyl fermions (WF). Depending on whether they conserve or violate the Lorenz symmetry, WSMs are classified as either type-I and type-II; however, until now type-II WFs are only indirectly verified experimentally. Here, by employing DFT assisted high-resolution 125Te solid-state NMR on the type-II WSM WTe2 we show that the various Te sites contribute distinctly to the Weyl electron bands, in a way that is clearly seen in the NMR signals. On this ground, by irradiating particular NMR frequencies, we succeeded in selectively probing type-II WFs and elucidate the evolution of the Fermi Surface (FS) with temperature, rendering NMR crystallography as one of the most suitable methods for exploring Weyl Physics.