A beam of light can do far more than illuminate a material, it can determine how electrical currents flow, how particles interact and even how light is emitted. Those possibilities were at the heart of the lecture delivered today as part of the QAMSS lecture series by Prof. Marcos H. D. Guimarães of University of Cambridge, who explored how light polarisation can be used to control electronic and optical behaviour in advanced layered materials.
The talk, titled Polarisation-Controlled Photocurrent and Many-Body Exciton Interactions in Layered Materials, examined how the unique crystallographic symmetries of low-dimensional quantum materials create new opportunities for manipulating photocarriers and excitons, the bound electron-hole pairs that play a central role in light–matter interactions.
Among the examples highlighted was the layered magnetic material CrPS₄, where photocurrent generation can be tuned through the polarisation of incoming light. The research demonstrates how the orientation of light can directly influence electronic transport, opening pathways towards more sophisticated optoelectronic devices.
The lecture also explored many-body exciton interactions in the monolayer semiconductor WSe₂. By exploiting valley-dependent properties, researchers are gaining new insight into how excitons interact in two-dimensional systems. Further work showed how engineering the underlying substrate can influence the polarisation of light emitted from transition metal dichalcogenides.
Together, the studies presented a picture of layered materials as an increasingly powerful platform for investigating quantum phenomena and controlling light–matter interactions. The findings could help shape future technologies ranging from photodetectors and light-emitting devices to next-generation quantum and optoelectronic systems.