Squeezing and steering electrons to advance valleytronics in graphene

Quantum physicist Josep Ingla-Aynes has found new ways to control valleytronics, an alternative for electronics where the charge is trapped in crystals instead of moving through a semiconductor. With the support of a Marie Curie grant, former postdoc Ingla-Aynes conducted research on valley effects in two layers of graphene in the Van der Zant Lab at Delft University of Technology. Their findings are published in Physical Review Letters [https://doi.org/10.1103/PhysRevLett.133.156301].

Valleytronics is the study of information processing that makes use of valleys: energy dips in crystals that can trap electrons. These valleys are not to be confused with literal pits; rather, they are pockets of low energy where electrons are inclined to rest. 

The study by Ingla-Aynes and fellow researcher Antonio Manesco demonstrates a device that generates electrical currents with a precisely controlled number of electrons at each valley. When electrons are squeezed through a narrow channel, they emerge as two jets which are valley polarized. By steering these jets with a magnetic field, the researchers can regulate  which jet enters through a second opening, gaining control on how many electrons end up in a specific valley. This control of valley population paves the way for realising electronic devices based on valleytronics.