Inverse Rashba Edelstein THz emission modulation induced by ferroelectricity in CoFeB/PtSe₂/MoSe₂//LiNbO₃ systems

Spintronic terahertz emitters, based on optically triggered spin-to-charge conversion processes, have recently emerged as a novel route toward compact and efficient THz sources. The next challenge for technologically relevant devices, however, remains to modulate the emission with low-energy consumption during operation. In order to achieve this, ferroelectric materials coupled to active spin-orbit layers such as two-dimensional transition metal dichalcogenides are potential candidates. In this work, we present the realization of a large area heterostructure of CoFeB/PtSe₂/MoSe₂ on a macroscopically bidomain LiNbO₃ substrate. Using THz time-domain spectroscopy, we show that the ferroelectric polarization direction induces a sizable modulation of the THz emission. We rationalize these experimental results by using band structure and spin accumulation calculations that are consistent with an interfacial spin-to-charge conversion mediated by the inverse Rashba-Edelstein effect at the MoSe₂/PtSe₂ interface and being tuned by ferroelectricity in the adjacent LiNbO₃ surface. This work demonstrates the relevance and technological potential of field effect spin-orbit architectures for novel THz technologies.