Quenched charge density wave and large in-plane upper critical field of self-intercalated bilayer NbSe2

Intercalation with extra atoms between atomic layers provides a new dimension to engineer transition metal dichalcogenide materials which show diverse many-body phenomena, such as charge density wave (CDW) and superconductivity. Here, we report the quenched CDW of 33.3% Nb-intercalated bilayer NbSe2 synthesized by the molecular beam epitaxy method. Our first-principles calculation shows that the absence of CDW in this self-intercalated ultrathin film is attributed to the strong valence bond and charge transfer between intercalated Nb and NbSe2 layers. Moreover, the large in-plane upper critical field beyond the Pauli limit of this thin film has been revealed by scanning tunneling spectroscopy. These findings not only deepen the understanding of the CDW and superconductivity of transition metal dichalcogenides, but also show a different approach to control the many-body electronic states which are potentially used for future electronics.