Electric-Field Tunable THz Emission via Quantum Geometry in Dirac Semimetal
Ziqi Li, Dongsheng Yang, Fei Wang, Yingshu Yang, Yuanyuan Guo, Bao Di, Tingting Yin, Chi Sin Tang, Teddy Salim, Lifei Xi, Chris Boothroyd, Yeng Ming Lam, Bo Peng, Marco Battiato, Hyunsoo Yang, Elbert E. M. Chia
Abstract
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, PtTe 2, 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 PtTe 2 /ferromagnetic heterobilayer, we electrically modulate the Fermi level and Berry curvature of PtTe 2, 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.