Electric-Field Tunable THz Emission via Quantum Geometry in Dirac Semimetal

Electric-field manipulation of spin degrees of freedom is pivotal for next-generation spintronics, yet nonvolatile control at terahertz (THz) frequencies remains elusive. Here, we harness the quantum geometry of a Dirac semimetal, PtTe₂, to achieve all-electrical tunability of THz spintronic emission under a constant magnetic field without field cycling or remanent magnetization. By integrating a ferroelectric substrate with a PtTe₂/ferromagnetic heterobilayer, we electrically modulate the Fermi level and Berry curvature of PtTe₂, thereby controlling its spin Hall conductivity in real time, yielding a 21% modulation of the THz emission amplitude. Density functional theory corroborates doping-driven shifts in Berry curvature that directly alter spin Hall conductivity, underscoring the key role of geometric phases in ultrafast spin-charge conversion. Our approach offers a low-complexity, energy-efficient, and nonvolatile route to tunable spin Hall THz devices, and we anticipate that these findings will open new avenues for harnessing quantum geometry in spin-based logic and ultrafast electronics.