Terahertz magnetization dynamics induced by femtosecond resonant pumping ofDy3+subsystem in the multisublattice antiferromagnetDyFeO3

Abstract

Resonant optical pumping of $f\ensuremath{-}f$ electronic transitions in the ${\mathrm{Dy}}^{3+}$ subsystem with femtosecond laser pulses in the multisublattice antiferromagnet ${\mathrm{DyFeO}}_{3}$ 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 ${\mathrm{Dy}}^{3+}$ ions on a femtosecond time scale with the induced longitudinal change of the magnetization reaching almost $1%$. We also show that for laser photon energies close to the $f\ensuremath{-}f$ resonance of ${\mathrm{Dy}}^{3+}$ ions, a minimum in the efficiency of spin-wave excitation in the ${\mathrm{Fe}}^{3+}$ subsystem via the inverse Faraday effect is observed. This observation reveals that the resonant photo-induced magnetization in the ${\mathrm{Dy}}^{3+}$ subsystem and the off-resonant excitation of spin waves in the ${\mathrm{Fe}}^{3+}$ subsystem are intrinsically competing processes.