Terahertz Pulses Detection in Thin Ferromagnetic Films Based on Zeeman-Torque effect

A method for detecting terahertz pulses using thin ferromagnetic films is presented. The method is based on the ultrafast change in magnetization of a ferromagnet due to the emergence of a torque-induced magnetic moment generated by the terahertz pulse (Zeeman-torque effect). A nonlinear optical ZnTe crystal was used as the source of terahertz radiation, producing pulses with a peak electric field strength of approximately 0.1 MV/cm. The magnetization rotation was recorded using the time-resolved magneto-optical Faraday effect. The experiment demonstrated the possibility of temporally strobing the magnetic response in Co(2 nm)/Pt(2 nm) and Co(10 nm) films in the frequency range up to several terahertz.