First Synthesis of EuS Nanoparticle Thin Film with a Wide Energy Gap and Giant Magneto-Optical Efficiency on a Glass Electrode

Abstract

Novel magneto-optical thin films composed of europium sulfide (EuS) nanoparticles on a glass electrode exhibit large magneto-optical efficiency and a wide energy gap. EuS nanoparticle thin films are prepared by the electrochemical reduction of a single-source precursor, a Eu­(III) dithiocarbamate complex (tetraphenylphosphonum tetrakis­(diethyldithiocarbamate) europium­(III)). The EuS nanoparticle thin films were prepared on indium–tin oxide (ITO)-coated glass electrodes and characterized by electrochemical analysis, scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy, laser scanning microscopy, and absorption spectroscopy. Faraday rotation spectra for estimation of the magneto-optical efficiency have clear positive and negative peaks, which are attributed to the 4f–5d transitions of the EuS thin films. The positive and negative peaks of the Faraday rotation spectrum are 525 and 680 nm, which are directly related to the energy gap of the EuS nanoparticle thin film (2.4 eV). That spectrum indicates that the EuS nanoparticle thin films are blue shifted in comparison with 7 nm diameter EuS nanoparticles (2.2 eV). The Verdet constant of the thin film was 11 mdeg/cm Oe at 525 nm, which is approximately 10 times larger than that of previously reported EuS nanoparticles