Probing the electronic structure of chemically-induced van der Waals heterostructures in VxTaS2

Layered transition metal dichalcogenides exhibit numerous exotic electronic phases, and their heterostructures are seen as promising platforms for quantum materials investigations and technologies. We found that dilute intercalation of vanadium into the 2H structural phase of TaS2 (VxTaS2) leads to intriguing changes in the electronic properties, including nearly a factor-of-3 enhancement of optimal superconducting Tc near x = 0.05.Using ARPES, we observe significant changes in the electronic structure with increasing x: The system evolves from the pure 2H band structure known for its charge density wave (CDW) and superconducting phases to a pure 1T electronic structure characterized by CDW and Mott interactions, as well as possible quantum spin glass behavior. Along the way, at intermediate x near the optimal Tc, the in-plane electronic structure is comprised of both 2H- and 1T-like bands. The weak out-of-plane electronic dispersion shows a distinct change in periodicity, indicating that these polymorphs are indeed stacked, rather than arranged side-by-side. By exploiting V intercalation as a means to assemble 2H/1T van der Waals heterostructures, we are granted an exceptionally clear spectroscopic window into each layer type, as well as the interplay between their electronic phases.