Spinvalley

Spinvalley refers to the coupled spin and valley degrees of freedom of charge carriers in certain materials, especially two-dimensional systems. In materials with multiple inequivalent energy extrema, or valleys, in the electronic band structure—notably monolayer transition metal dichalcogenides such as MoS2, WS2, MoSe2, and WSe2—the combination of strong spin–orbit coupling and broken inversion symmetry links an electron’s spin to its valley index. This spin–valley locking means that carriers in a given valley tend to have a preferred spin orientation, enabling selective control of spin and valley populations.

The coupling gives rise to valley-dependent optical selection rules: circularly polarized light can preferentially excite one valley over the other, and the emitted photoluminescence can reflect the valley and spin polarization. The physics is described in terms of Berry curvature, orbital magnetic moments, and the topology of the electronic bands, which influence both transport and optical responses. Experimental observations include valley-selective excitation and detection, valley polarization and coherence, and measurements related to the valley Hall and spin Hall effects.

Potential applications span valleytronics and spintronics, with concepts such as valley filters, spin–valley qubits for quantum information, and integrated devices that exploit both spin and valley degrees of freedom. Challenges remain, including maintaining coherence and polarization at room temperature, mitigating intervalley scattering, and developing scalable materials and device architectures. Spinvalley remains an active area of condensed matter physics and materials science, bridging spintronics, valleytronics, and two-dimensional material research.