Atomic-layer controlled THz spintronic emission from two dimensional PtSe2/ferromagnet heterostructures

Spintronic emitters have become important THz sources with broadband emission through ultrafast spin-to-charge conversion. This has recently driven investigations of two-dimensional materials as spintronic THz sources. One such 2D material is the transition-metal dichalcogenide PtSe2. Here we present THz spintronic sources based on high quality epitaxially grown CoFeB/PtSe2/graphene heterostructures, with PtSe2 thicknesses ranging from 1 to 15 monolayers. The unique thickness dependent PtSe2 bandstructure permits to demonstrate different origins of the THz emission - from the inverse Rashba-Edelstein effect in monolayer PtSe2 to the inverse Spin-Hall effect for multilayers. This bandstructure flexibility makes PtSe2 an ideal THz spintronic 2D material.