Spin-Valley Transport in Two-Dimensional Materials

Spin-valley transport in two-dimensional materials exploits the coupling between electron spin and valley degrees of freedom in atomically thin crystals. In transition metal dichalcogenide monolayers, graphene analogues, and their silicon or germanium counterparts, strong spin–orbit coupling lifts spin degeneracy and locks spin orientation to specific momentum valleys. This gives rise to a rich variety of phenomena including the quantum spin Hall effect, the valley Hall effect, and various topological insulating phases. Control of spin-valley polarisation can be achieved through external fields, strain or optical excitation, enabling the design of spintronic and valleytronic devices that promise high-speed, low-power information processing. Edge states in topological phases support dissipationless transport, while engineered superlattices and heterostructures allow for selective gating of spin and valley currents. Recent advances have revealed new mechanisms for inducing and manipulating spin-valley polarisation, illustrating the potential for practical applications in sensing, quantum computing and communications technologies.

Research from Nature Portfolio

Recent studies have demonstrated the modulation of antichiral edge states in zigzag honeycomb nanoribbons by applying tailored side potentials. Such potentials lift the spin degeneracy of boundary modes in both K and K′ valleys, generating multiple antichiral states and enabling a three‐terminal spin/charge switch suitable for future spintronic architectures. Foundational work in monolayer transition metal dichalcogenides has also revealed that materials formerly considered direct-gap semiconductors can exhibit an indirect quasiparticle gap. This re-evaluation of valley populations and exciton binding energies has profound implications for the design of valleytronic devices, as it reshapes our understanding of excitonic thermal populations and inter-valley transport pathways.

Spin-Valley Transport in Two-Dimensional Materials publication trend

The graph below shows the total number of articles in spin-valley transport in two-dimensional materials across all publications each year (not limited to Nature Index journals).

Technical terms

Spin–orbit coupling: Interaction between an electron’s spin and its orbital motion that lifts spin degeneracy in energy bands.

Valley degree of freedom: Binary quantum index (K and K′) labelling inequivalent momentum extrema in honeycomb lattices.

Quantum spin Hall effect: Topological state featuring dissipationless spin-polarised edge currents protected by time-reversal symmetry.

Valley Hall effect: Transverse separation of electrons into different valleys under an applied in-plane electric field.

Chiral edge state: Unidirectional boundary mode that propagates in a single direction along the edge of a topological insulator.

Antichiral edge state: Boundary mode in which spin-polarised channels at both edges propagate in the same direction due to symmetry breaking.

Topological insulator: Material that is insulating in the bulk but hosts conducting edge or surface states protected by topology.

References

1. Modulation of antichiral edge states in zigzag honeycomb nanoribbons by side potentials. Communications Physics (2023).
2. Evidence of indirect gap in monolayer WSe2. Nature Communications (2017).
3. Faraday rotation and transmittance as markers of topological phase transitions in 2D materials. SciPost Physics (2024).
4. Photoinduced phases in jacutingaite monolayer. Physical Review Research (2023).
5. Topological spin–valley filtering effects based on hybrid silicene-like nanoribbons. New Journal of Physics (2020).