Monolayer transition metal dichalcogenides (TMDCs) with broken inversion symmetry have shown unique optical response properties. We calculate the topological phase shift of MoS2 as a prototype of TMDs systems involving the Berry connection in the presence of inter-valley scattering processes. Our results are based on two alternative approaches; quantum kinetic theory where we calculate the non-equilibrium distribution function of each band and another approach based on the exciton absorption where the electron-electron interaction is considered. We find the shift current peaks emerge at the inter-band absorption threshold in the same valley and at a transition point between the valence and conduction bands of various valleys in the doped system. We demonstrate the significant enhancement of shift current owing to the inter-valley scattering processes. Our findings provide a new platform for nonlinear light-matter interaction engineering.
About the presenter
Reza Asgar is a theoretical condensed-matter physicist working with Prof Dimitre Culcer at UNSW. Reza’s particular interest is in the nonlinear optical response in low-dimensional advanced materials, seeking an answer to the question ’How do we get maximum benefits in the case of light-matter interaction?’ A deep understanding of the phenomena is needed to discover promising materials in optoelectronics and other technologies. Within FLEET’s Reza’s work falls under Research theme 1 topological materials.