Superconductivity in Transition Metal Dichalcogenides

Transition metal dichalcogenides (TMDs) are layered compounds of the form MX₂, where M denotes a transition metal and X a chalcogen. Their van der Waals bonded sheets can be exfoliated to monolayer or few-layer films, preserving unconventional electronic phases in two dimensions. Superconductivity in TMDs arises from a delicate interplay between electron–phonon coupling, reduced dimensionality and competing charge-density waves. In monolayer and few-layer limits, strong spin–orbit coupling and broken inversion symmetry give rise to protections against Pauli depairing, often referred to as Ising superconductivity. Dimensional reduction can enhance the superconducting transition temperature and upper critical field, while intercalation or ionic gating permits tuning of carrier density. The combination of robust superconductivity, tunability and compatibility with van der Waals heterostructures positions TMDs as promising materials for superconducting electronics, single-photon detectors and platforms for topological superconductivity.

Research from Nature Portfolio

Recent studies have demonstrated a topotactic conversion route to fabricate superconducting TMD nanocircuits directly on a wafer scale. Prepatterned metal precursors are transformed into meandering NbSe₂ nanowires and other geometries without degrading the superconducting properties, enabling circuits for single-photon detection and complex hole arrays.

Investigations of monolayer 2H-TaS₂ and 2H-NbSe₂ have revealed the impact of antisymmetric spin–orbit coupling on superconducting pairing. High-field measurements show upper critical fields far exceeding the Pauli limit, sustained by spin–valley locking. This work has established spin–orbit coupling as a key parameter in stabilising two-dimensional superconductivity and guiding the search for unconventional paired states.

Superconductivity in Transition Metal Dichalcogenides publication trend

The graph below shows the total number of articles in superconductivity in transition metal dichalcogenides across all publications each year (not limited to Nature Index journals).

Technical terms

Transition metal dichalcogenides: Layered materials of composition MX₂, comprising a transition metal M and chalcogen X, bonded by van der Waals forces.

Van der Waals gap: Weakly bonded interlayer space between adjacent TMD sheets.

Critical temperature (Tc): Temperature below which a material exhibits zero electrical resistance.

Critical current density (Jc): Maximum current density a superconductor can carry without losing its superconducting state.

Spin–orbit coupling (SOC): Interaction between an electron’s spin and its orbital motion, influencing pairing symmetry in superconductors.

Nodal superconductivity: Superconducting state in which the energy gap goes to zero at certain points or lines on the Fermi surface.

Topotactic conversion: Chemical transformation that retains the crystal framework while converting precursor materials into the target phase.

Ising superconductivity: Two-dimensional superconductivity protected by strong in-plane spin–orbit coupling, leading to high in-plane critical fields.

References

1. Evidence of Nodal Superconductivity in Monolayer 1H‐TaS2 with Hidden Order Fluctuations. Advanced Materials (2023).
2. Topotactic fabrication of transition metal dichalcogenide superconducting nanocircuits. Nature Communications (2023).
3. Enhanced Superconductivity and Critical Current Density Due to the Interaction of InSe2 Bonded Layer in (InSe2)0.12NbSe2. Journal of the American Chemical Society (2024).
4. Superconductivity Series in Transition Metal Dichalcogenides by Ionic Gating. Scientific Reports (2015).
5. Tuning Ising superconductivity with layer and spin–orbit coupling in two-dimensional transition-metal dichalcogenides. Nature Communications (2018).
6. Enhanced superconductivity in atomically thin TaS2. Nature Communications (2016).