Terahertz magnetization dynamics induced by femtosecond resonant pumping of Dy3+ subsystem in the multisublattice antiferromagnet DyFeO3

Resonant optical pumping of f - f electronic transitions in the Dy3+ subsystem with femtosecond laser pulses in the multisublattice antiferromagnet DyFeO3 produces a strongly pronounced effect on the induced magnetization dynamics. Analyzing the polarization and spectral properties of the emitted THz radiation, we infer that the resonant pumping magnetizes the partially ordered Dy3+ ions on a femtosecond time scale with the induced longitudinal change of themagnetization reaching almost 1%. We also showthat for laser photon energies close to the f - f resonance of Dy3+ ions, a minimum in the efficiency of spin-wave excitation in the Fe3+ subsystem via the inverse Faraday effect is observed. This observation reveals that the resonant photo-induced magnetization in the Dy3+ subsystem and the off-resonant excitation of spin waves in the Fe3+ subsystem are intrinsically competing processes.