The Sir Martin Wood Prize Lecture 2016: Dr Takuya Satoh, "Generation and control of magnetic excitations by polarized light in antiferromagnets and ferrimagnets".

1 Jun 2016 - 2:00pm to 3:00pm
Martin Wood Complex, Department of Physics, University of Oxford, Parks Road, Oxford, OX1 3PU
Martin Wood Lecture Theatre
General public (Age 14+)

Generation and control of magnetic excitations by polarized light in antiferromagnets and ferrimagnets

Dr Takuya Satoh,Faculty of Science, Kyushu University

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 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 slot of the excitation beam. This fact lead to the direction 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 and 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. Ida, T. Higuchi, M. Fiebig and T. Shimura, Nature Photonics 9, 25 (2015).

For more information contact: 

Olivia Hawkes
Condensed Matter Physics
T: (0)1865 272225