Spin-Orbit-Torque-Driven Terahertz Oscillations in Pt/KFe3(OH)6(SO4)2/W Trilayer Structure.

We propose a nanoscale terahertz (THz) signal generator based on a Pt/KFe3(OH)6(SO4)2/W trilayer structure that produces stable THz output under direct-current driving. Spin currents injected from the Pt layer generate spin-orbit torque (SOT), exciting the magnetic moments of the noncollinear antiferromagnet (AFM) KFe3(OH)6(SO4)2 and inducing steady magnetization oscillations. These oscillations generate THz alternating-current (AC) signals, which are electrically detected via the inverse spin Hall effect (ISHE) in the W layer. The asymmetric heavy-metal/AFM/heavy-metal configuration, featuring opposite spin Hall angles, enables efficient spin-current injection and signal readout. Micromagnetic simulations and theoretical analysis reveal that the THz signal originates from the asymmetric distribution of Dzyaloshinskii-Moriya interaction (DMI) energy. A quantitative relationship between excitation current and signal output is established, and tunable frequency control with reduced threshold current is achieved by optimizing material and structural parameters.