Layer controlled terahertz photocurrents in 2D transition metal dichalcogenides

Transition metal dichalcogenides (TMD) are promising 2D materials with possible usage in wide range of applications, owing to a bandstucture flexibility that can be uniquely engineered depending on the number of atomic layers. This can be probed by the generation of ultrafast photocurrents with femtosecond excitation, leading to emission of terahertz picosecond-scale pulses that depends on nonlinearities of the studied material. Here we will show layer controlled nonlinearities in semi-conducting and sem-imetal 2D PtSe2, opening up a new class of circular dichroism materials beyond the monolayer limit, and impacting a range of domains from THz valleytronics to THz spintronics.