Researchers develop a graphene-based topological valley valve

Researchers from Penn State University developed a topological valley valve, which controls electron flow. Using electron "beam splitters", the researchers achieved high-level of electron control.

Using bilayer graphene, the researcher created electron waveguides created by gates defined with extreme precision using state-of-the-art electron beam lithography.By controlling the topology of the waveguides (the valley-momentum locking of the electrons), the researchers can control electron flow.

Researchers find a way to achieve current valley separation in graphene

Researchers from Ohio University have found a simple yet effective way to achieve current valley separation in graphene. The idea is based on inversion symmetry, or the creation of properly oriented obstacles that break an important symmetry of the graphene crystal.

Valley current asymmetry in graphene

This is a theoretical work, but the researchers say that the results could enable seperating and controling valley currents in graphene in real experiments which will hopefully lead to the utilization of graphene in future valleytronics devices.

Researchers use bi-layer graphene to create a device that control electron flow based on the valley degree of freedom

Researchers from Penn State University demonstrated a new device, based on bi-layer graphene, that provides an experimental proof of the ability to control electron-flow by the valley degree of freedom. This is still an early-stage development, but could be seen as an important step towards valleytronics.

Bi-layer graphene based valleytronics experiment (Penn State)

The device is built from a bi-layer graphene, and gates above and below the graphene layer. Adding an electric field perpendicular to the plane opens a bandgap in the bi-layer graphene, and a physical gap (70 nanometer in height) is left, in which one-dimensional metallic states (wires) exists. These states act as valleytronics valves.