Terahertz radiation from antiferromagnetic MnO excited by optical laser pulses

Terahertz (THz) radiation from antiferromagnetic (AFM) MnO excited by femtosecond laser pulses has been investigated. The radiated THz pulse consists of a single-cycle broadband pulse and an oscillating component with a frequency of 0.83 THz at 10 K. The oscillations are magnetic dipole radiation from optically excited AFM magnons. We found that the peak amplitude of the broadband pulse from MnO increases as the temperature decreases and is significantly enhanced below AFM order temperature. The origin of the broadband pulse radiation observed below AFM order temperature can be attributed to second-order nonlinear optical effects depending on the AFM order.