Magneto-optical properties of transparent divalent iron phosphate glasses

We have prepared glasses having x Fe O ⋅ ( 100 − x ) P 2 O 5 (mol%) ( x = 50.0 , 54.0 , 57.1 ) compositions by melting under mild reducing condition and found that these glasses exhibit fairly high transmittance in the visible range and large Faraday effect at the wavelength of about 400 nm . Fe 57 Mössbauer spectra confirm that almost all the iron ions are present as Fe 2 + in the glasses. A spin glass transition is observed at low temperatures in the temperature dependence of magnetic susceptibility. Intense optical absorption in the ultraviolet and infrared wavelength ranges occurs by the charge transfer transition from O 2 − to Fe 2 + and the intra-atomic d - d transition, respectively. The analysis on the wavelength dependence of the Faraday rotation angle using the Van Vleck-Hebb theory has revealed that the charge transfer transition contributes more significantly to the Faraday effect owing to the large effective transition probability, which is comparable to those reported for glasses containing 4 f rare-earth ions. The magneto-optical figure of merit shows a maximum at around 380 nm .