Correction to "Terahertz Magnon-Polaritons in TmFeO3".

[This corrects the article DOI: 10.1021/acsphotonics.7b01402.].

Modelling nonlocal nonlinear spin dynamics in antiferromagnetic orthoferrites.

Excitation with an ultrashort light pulse is arguably the only way to control spins in antiferromagnetic materials at both the nanoscale in space and ultrafast time scale. While recent experiments highlighted tantalising opportunities for spin switching and magnonics in antiferromagnets, the theoretical description of antiferromagnetic spin dynamics driven by strongly localised and ultrashort excitation is in its infancy. Here we report a theoretical model describing the nonlocal and nonlinear spin response to the excitation by light. We show that strongly localised ultrafast excitation can drive spin switching, which propagates in space and acts as a source of spin waves. Our theoretical formalism is readily available to describe current and future ultrafast spectroscopy experiments in antiferromagnets.

Terahertz Magnon-Polaritons in TmFeO3.

Magnon-polaritons are shown to play a dominant role in the propagation of terahertz (THz) waves through TmFeO3 orthoferrite, if the frequencies of the waves are in the vicinity of the quasi-antiferromagnetic spin resonance mode. Both time-domain THz transmission and emission spectroscopies reveal clear beatings between two modes with frequencies slightly above and slightly below this resonance, respectively. Rigorous modeling of the interaction between the spins of TmFeO3 and the THz light shows that the frequencies correspond to the upper and lower magnon-polariton branches. Our findings reveal the previously ignored importance of propagation effects and polaritons in such heavily debated areas as THz magnonics and THz spectroscopy of electromagnons. It also shows that future progress in these areas calls for an interdisciplinary approach at the interface between magnetism and photonics.

Colossal magneto-optical modulation at terahertz frequencies by counterpropagating femtosecond laser pulses in Tb3Ga5O12.

Single-frequency terahertz modulation of the magneto-optical Faraday effect with a record amplitude of the polarization rotation of ∼0.5° is achieved using a slab of the etalon Faraday rotator crystal Tb3Ga5O12. The modulation is the result of the interaction of two counterpropagating laser pulses via the optical Kerr effect. The frequency of the modulation is determined by the applied magnetic field and is continuously tunable in a terahertz frequency range between 0 and 0.7 THz.