Researchers demonstrate how few-cycle linearly polarized pulses can induce a high degree of valley polarization

Scientists from several research institutes in Germany and the UK have demonstrated that few-cycle linearly polarized pulses can induce a high degree of valley polarization.

The mechanism to induce such polarization does not rely on the optical selection rules, and therefore can be in principle used in inversion symmetric materials, such as TMD bilayers or graphene. This could enable the design of ultrafast valleytronic devices.

The researchers say that their approach takes advantage of the sub-cycle control of the electron motion by controlling the oscillations of the electric field under the envelope, and allows for full control of the valley initialization step on a few-femtosecond timescale.