The 222nd Special CMSM seminar   


Opto-Magnonics: Spin-Wave Manipulation by Light Pulses

Prof. T. Satoh
Laboratory for Optical Condensed Matter Physics, Kyushu University.

Date & Time: 14:00 - 15:00, September 21st (Wed), 2016.
Place: 7F Small Seminar Room, Sengen

Abstract:

  The resonance frequency of spin oscillation in antiferromagnets is extremely high due to the exchange interaction between adjacent spins, and faster magnetization control had been expected. However, it was believed that the inverse Faraday effect, that is the inverse effect of the magneto-optical Faraday effect, does not act on pure antiferromagnets with zero net magnetization. Optical control of antiferromagnets had not been reported. We succeeded in excitation of spin oscillation in NiO by illuminating circularly polarized light pulses and in optical control of an antiferromagnet [1].
  We also demonstrated, for the first time, time and phase resolved imaging of spin wave propagation in a ferrimagnet induced via the inverse Faraday effect [2]. It was shown that the wave number distribution of the excited spin wave is proportional to the frequency component of spatial spot of the excitation beam. This fact lead to the directional control of spin wave propagation, thus demonstration of spin wave manipulation by using spatially shaped optical pulses [2].
  Finally, we have demonstrated the one-to-one transfer of the polarization eigenstates of a fully polarized pump light wave onto the magnetic eigenmodes of a three-sublattice antiferromagnet. We converted the magnetic information back into the optical polarization eigenstate of a probe light wave in an equally one-to-one process [3]. These results will pave the way to new fields of "terahertz-spintronics" and "opto-magnonics" for generating and controlling magnetic excitations by polarized light.

[1] T. Satoh, S.-J. Cho, R. Iida, T. Shimura, K. Kuroda, H. Ueda, Y. Ueda, B. A. Ivanov, F. Nori, and M. Fiebig, Physical Review Letters 105, 077402 (2010).
[2] T. Satoh, Y. Terui, R. Moriya, B. A. Ivanov, K. Ando, E. Saitoh, T. Shimura, and K. Kuroda, Nature Photonics 6, 662 (2012).
[3] T. Satoh, R. Iida, T. Higuchi, M. Fiebig, and T. Shimura, Nature Photonics 9, 25 (2015).