Terahertz magnetic field induced coherent spin precession in YFeO 3

We present the magnetic dipole transition at 0.299THz excited by magnetic component of terahertz electromagnetic pulse in an antiferromagnetic YFeO 3 crystal. The impulsive magnetic field of the terahertz pulse tilts the macroscopic magnetization, causing deviation from the equilibrium position, which is manifested by a sharp absorption at the frequency of the quasiferromagnetic mode of the crystal. The rotating coherent macroscopic magnetization radiates elliptically polarized emission at the frequency of the quasiferromagnetic resonance due to the dichroic absorption in the crystal.