Modulated terahertz generation in femtosecond laser plasma filaments by high-field spintronic terahertz pulses

Strong-field terahertz (THz) light-matter interaction provides various nonlinear control approaches in condensed matter physics, energy and material sciences, electron acceleration, and manipulation. Recently developed spintronic THz emission with minimum complexities has been demonstrated to have the capability for generating high field strengths. Up to now, nonlinear applications based on the spintronic THz transients have yet been realized. Here, we report THz emission from two-color femtosecond laser plasma filaments modulated by a 60-kV/cm THz pulse from W/CoFeB/Pt heterostructures. Enhanced THz radiation based on electron acceleration in plasma is recorded when the direction of the spintronic THz modulating field is in line with that of the electron movement. This behavior is quantitatively reproduced by a local current model of the plasma THz source. Our experimental and theoretical results may inspire further nonlinear THz investigation and accelerate ultrafast THz engineering in matter.& nbsp;Published under an exclusive license by AIP Publishing.