Full superconducting dome of strong Ising protection in gated monolayer WS ₂

Abstract

Many recent studies show that superconductivity not only exists in atomically thin monolayers but can exhibit enhanced properties such as a higher transition temperature and a stronger critical field. Nevertheless, besides being unstable in air, the weak tunability in these intrinsically metallic monolayers has limited the exploration of monolayer superconductivity, hindering their potential in electronic applications (e.g., superconductor-semiconductor hybrid devices). Here we show that using field effect gating, we can induce superconductivity in monolayer WS grown by chemical vapor deposition, a typical ambient-stable semiconducting transition metal dichalcogenide (TMD), and we are able to access a complete set of competing electronic phases over an unprecedented doping range from band insulator, superconductor, to a reentrant insulator at high doping. Throughout the superconducting dome, the Cooper pair spin is pinned by a strong internal spin-orbit interaction, making this material arguably the most resilient superconductor in the external magnetic field. The reentrant insulating state at positive high gating voltages is attributed to localization induced by the characteristically weak screening of the monolayer, providing insight into many dome-like superconducting phases observed in field-induced quasi-2D superconductors.

Towards the insulator-to-metal transition at the surface of ion-gated nanocrystalline diamond films

“…As ∆n 2D increases, β first decreases and then saturates around ∼ 0.44 for ∆n 2D 1.5 · 10 14 e + /cm 2 : the AL is unable to reach the QC point (dashed magenta line) and cross into the disordered metal regime of the underlying bulk (shaded grey area). We ascribe this behavior to extra scattering centers introduced by the ions in the EDL at the solid/electrolyte interface [43][44][45][46][47], an effect that can even lead to re-entrant MITs in extremely surface-sensitive materials [48,49]. The gateinduced disorder shifts the Anderson transition to larger doping levels, eventually compensating the concomitant increase in ∆n 2D and locking the AL in the QC regime on the insulating side of the MIT.…”

Dominant role of processing temperature in electric field induced superconductivity in layered ZrNBr

“…Furthermore, the electric field could induce a clear percolation transition from a short-range magnetically ordered insulator to a robust long-range ferromagnetic metal in La 1−x Sr x CoO 3−δ [12,13]. On the other hand, the developed control of the electric field makes it possible to access a complete set of competing electronic phases from band insulators and superconductors, to a reentrant insulator on the monolayers of WS 2 [14].…”

Type-II Ising Superconductivity in Two-Dimensional Materials with Spin-Orbit Coupling

“…Previous studies found that Rashba-type SOC in 2D noncentrosymmetric superconductors can create novel mixed singlet-triplet pairing and leads to a moderate enhancement of B c2 [12,13]. Very recently, a new kind of 2D noncentrosymmetric superconductivity, called Ising superconductivity, has been discovered in transition metal dichalcogenides (TMDs) [14][15][16][17][18][19][20]. In these materials, the SOC generates Zeeman-like spin splittings for electrons near the K and K valleys.…”