Using ultrafast laser pulses we demonstrate adiabatic control of the bandstructure of monolayer WS2 through Floquet engineering. In other words the periodic electric field of the laser pulse dresses the Bloch bands of the semiconductors. Interactions between the dressed bands then cause energy shifts, avoided crossings and the potential to induce a topological phase transition.
The use of coherent spectroscopy to excite and probe coherent superpositions of ground-excited states, and/or of K-K’ excitons allows detailed insight into the interactions between excitons as well as interactions with the environment. Understanding these processes is crucial for our understanding of how we may drive topological bandstructures. Our initial measurements reveal decoherence times at room temperature of 35fs, and that we are able to adiabatically control the bandstructure with pulses less than 30fs in duration.
About the presenter
Dr Stuart Earl is a postdoctoral researcher working with A/Prof Jeffrey Davis at Swinburne University, applying ultrafast multidimensional spectroscopy techniques to investigate non-equilibrium topological phenomena in emerging materials for FLEET’s Research Theme 3 and Research theme 2.