Researchers demonstrate the direct coupling of light to valley current

Researchers from the Max Born and Max Planck institutes have shown that the few cycle limit of circularly polarized light is imbued with an emergent vectorial character that allows direct coupling to the valley current. The underlying physical mechanism involves the emergence of a momentum space valley dipole, the orientation and magnitude of which allows complete control over the direction and magnitude of the valley current.

The researchers demonstrate this effect via minimal tight-binding models both for the visible spectrum gaps of the transition metal dichalcogenides as well as the infrared gaps of biased bilayer graphene.