Researchers suggest a way to pump carriers valley-selectively

Researchers at the University of Geneva proposed a novel approach to optically ‘pump’ carriers valley-selectively using a high-purity bismuth crystal.

UNIGE bismuth optically pump carriers valley selectively

In bismuth there are three valleys and the electrons orbit in magnetic field that are strongly elongated along one direction due the interaction with the atomic lattice. Each valley has its own direction - which means that the direction can be used to discriminate between the valleys.