The research group including Tohoku University succeeded in developing a magneto-optical material with a completely new idea for the first time in the world.The developed material has a nanostructure in which nanometer-sized magnetic metal particles called a nanogranular structure are dispersed in ceramics, and is a huge Faraday that is about 40 times larger than the conventional light of the wavelength used for optical communication. It is said to show an effect.

 The Faraday effect is a phenomenon in which the plane of polarization of light transmitted through a magnetic material rotates in light incident on the magnetic field in a direction parallel to the magnetic field applied to the magnetic material.Materials exhibiting the Faraday effect are widely used in optical devices, especially optical communication systems, and are indispensable for advanced information technology.
However, since the discovery of bismuth iron garnet in 1972, no more promising material has been found for the Faraday effect material, and the design and performance of devices using the Faraday effect have been limited so far.

 The nanogranular material developed this time has a structure in which iron-cobalt alloy fine particles (granule) with a particle size of several nanometers are dispersed in a substance (matrix) made of fluoride ceramics.Due to this structure, the magnetic moment of iron and cobalt atoms increases at the interface between the granule and the matrix, and a large Faraday effect can be obtained.

 This research has developed a new Faraday effect material that has been sought after worldwide but has not been realized for 45 years.Furthermore, its size is about 40 times that of the conventional one, and since it is a thin film material, the degree of freedom in optical device design is greatly expanded.By developing the results of this research, it will be possible to miniaturize and integrate optical devices, and it will be possible to realize so-called "photon devices" in place of electronic devices.

Paper information:[Scientific Reports] Giant Faraday Rotation in Metal-Fluoride Nanogranular Films

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