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Optical Condensed Matter Physics

  • Takuya Satoh, Associate Professor
Our group studies experimentally the interaction of light with magnetic/dielectric materials. In particular, we are interested in ultrafast and coherent control of magnetism by use of temporally and spatially shaped femtosecond light pulses, and understanding of the mechanisms. Current research topics are as follows:
  1. Terahertz Spintronics
  2. Opto-Magnonics

Terahertz Spintronics

Figure 1. Pump-probe experiment

We study ultrafast spin manipulation by using light. Light pulses will be temporally shaped to achieve the most efficient spin manipulation. We focus on antiferromagnets, which possess the highest frequency (~THz). The combination of temporally shaped light pulses and antiferromagnetic materials will enable us to demonstrate fast and arbitrary spin manipulation.

Opto-Magnonics

Figure 2. Temporally shaped light pulse

We propose a nonthermal spin wave generation technique that utilizes a circularly polarized light pulse via the inverse Faraday effect. We also propose a technique for manipulating the direction of spin wave propagation by shaping a light spot at the sample surface. This will be the first step in the new field of "opto-magnonics".

Figure 3. Femtosecond laser system

The final goal is to pioneer a new field of "opto-magnonics" by exploiting ultrashort-light pulses and to realize ultrafast opto-magnetic switching devices.

Figure 4. Spin wave

T. Satoh et al., Phys. Rev. Lett. 105, 077402 (2010).
T. Satoh et al., Nature Photonics 6, 662-666 (2012).
T. Satoh et al., Nature Photonics 9, 25-29 (2015).