Glass - Back to the Future!

Presenting Author:
Yuko Nakatsuka

article posted 19 May 2016

Yuko Nakatsuka is a PhD student of Graduate School of Engineering, Kyoto University, Japan. Her research interests are magnetic and magneto-optical properties of oxide glasses containing transition elements. She received master’s degree in engineering in Kyoto University in March 2014. Since April 2015, she has been also a JSPS (Japanese Society for the Promotion of Science) Research Fellow (DC2). She was a visiting student at the Laboratory of Glass Science with Prof. Dr. Lothar Wondraczek in Otto Schott Institute of Materials Research, Friedrich Schiller University Jena, Germany from March 2015 to February 2016.

Large Faraday Effect of Amorphous Iron-containing Silicate Thin Films

Yuko Nakatsuka*1,2, Sindy Fuhrmann2, Kilian Pollok3, Torsten Wieduwilt4, Falko Langenhorst3, Lothar Wondraczek2, Koji Fujita1, Shunsuke Murai1, Katsuhisa Tanaka1

Amorphous oxides containing transition elements have attracted much attention because some of them are transparent to visible light and possess a Faraday effect. Faraday effect is applicable to optical devices such as optical isolators and switches. We have prepared amorphous thin films with nominal compositions of xFeO·(100–x)SiO2 (x = 10, 33, 50, 67 in mol%) on silica glass substrates by using a pulsed laser deposition method. The amorphous FeO-SiO2 thin films show a large Faraday effect especially in the short wavelength range of visible light, as shown in Figure 1. The absolute value of the Verdet constant for 67FeO·33SiO2 is 75.2 min/Oe·cm at 380 nm, which is larger by one order of magnitude than Eu2+-containing glasses; the Verdet constant of 58.0EuO·12.0Al2O3·20.0B2O3·10.0SiO2 is –1.03 min/Oe·cm at 633 nm (Akamatsu et al, Opt. Mater. 35 (2013) 1997). From X-ray photoelectron and X-ray absorption near edge structure spectroscopies, it was revealed that iron cations are mainly present as Fe2+, but the Fe0 state was also detected. These results are consistent with the relatively high refractive indices of the thin films. Quite tiny (~1 nm) metallic iron crystals were observed in dark field transmission electron microscope images. It is supposed that the large Faraday effect is due to the presence of metallic iron clusters.

Figure 1 Wavelength dependence of Verdet constant of the films.

1Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto, 615-8510, Japan
2Otto Schott Institute of Materials Research, Friedrich Schiller University Jena, Fraunhoferstr. 6, 07743, Jena, Germany
3 Institute of Geosciences, Friedrich Schiller University Jena, Carl-Zeiss-Promenade 10, 07745, Jena, Germany
4 Leibnitz Institute of Photonic Technology, Friedrich Schiller University Jena, Albert-Einstein-Str. 9, 07745, Jena, Germany