Terahertz Phase Inversion via Field‐Free Spin‐Orbit Torque Switching in an Antenna‐Integrated Spintronic Heterostructure

We demonstrate microsecond‐timescale electrical control of the terahertz (THz) emission phase in broadband field‐free spintronic THz emitters, enabling megahertz‐rate phase inversion while overcoming the kilohertz limitations of conventional mechanical and field‐driven approaches. Our device integrates an H‐dipole antenna with a spintronic heterostructure exhibiting uniaxial magnetic anisotropy, enabling deterministic spin‐orbit torque induced in‐plane magnetization switching without external magnetic fields. The corresponding THz phase inversion is directly observed in the time domain signal, by applying electrical pulses on the bias striplines of the H‐dipole. This field‐free operation reduces system complexity while significantly extending modulation bandwidth. Our results establish electrically programmable spintronic THz emitters that could be used to develop a compact and scalable platform for integrated on‐chip THz devices and ultrafast applications, including phase‐sensitive spectroscopy and near‐field imaging, where high‐speed and precise control of THz waveforms is essential.