Researchers at the Berkeley Lab have discovered topologically protected 1D electron conducting channels at the domain walls of bi-layer graphene. These conducting channels are “valley polarized”, meaning they can serve as filters for electron valley polarization in future valleytronics applications like quantum computers. Valleytronics involves the coding of data in the wavelike motion of electrons as they speed through a semiconductor, and these 1D valley-polarized conducting channels indicate that graphene could be of value for valleytronics applications in the future.
The researchers used focused beams of infrared light to image bi-layer graphene layer-stacking domain walls on device substrates. Field effect devices fabricated over these domain walls revealed the 1D conducting channels, which featured a ballistic length of about 400 nanometers at 4 kelvin.Up until now, most valleytronics research has focused on 2D semiconductors known as MX2 materials such as molybdenum or tungsten, sandwiched between two layers of chalcogen atoms, such as sulfur. The results of this study demonstrate that protected topological phases can also be realized in bi-layer graphene, making it potentially useful for valleytronic applications.