Full Length Article Magneto-optical properties of Ce 3+ and Tb 3+ -doped silico-phosphate sol-gel thin films C.R. Stefan a , M. Elisa a,⇑ , I.C. Vasiliu a , B.A. Sava b , L. Boroica b , M. Sofronie c , F. Tolea c , M. Enculescu c , V. Kuncser c , A. Beldiceanu d , A. Volceanov e , M. Eftimie e a National Institute of R & D for Optoelectronics INOE 2000, 409 Atomistilor Str., 77125 Magurele, Jud. Ilfov, Romania b National Institute for Laser, Plasma and Radiation Physics, POB MG-7, 77125 Magurele, Romania c National Institute of Materials Physics, POB MG-7, 77125 Magurele, Romania d S.C. ProOptica S.A., 67 Gheorghe Petrascu Str., Bucharest, Romania e University Politehnica of Bucharest, Faculty of Applied Chemistry and Materials Science, 1 Polizu Str., Bucharest, Romania article info Article history: Received 15 December 2017 Revised 14 March 2018 Accepted 7 April 2018 Available online 11 April 2018 Keywords: Films Silico-phosphate glass Rare-earth-doped glass Sol-gel method Magnetic properties Magneto-optical properties abstract Ce 3+ and Tb 3+ -doped silico-phosphate films were obtained by using the sol-gel method, followed by the spin-coating deposition on silicon substrate. The homogeneity of the films was investigated by the cono- scopy method. It was observed that the analysed films are isotropic but relatively inhomogeneous due to the specificity of the deposition technique. The morphology of the sol-gel films was investigated by Scanning Electron Microscopy and Atomic Force Microscopy. The elemental composition was determined by Energy Dispersive X-ray analysis. The magneto-optical investigations evidenced the capability of Ce and Tb-doped films of less than 2 mm thickness to produce measurable Kerr rotations of 1 mdeg/T and 0.28 mdeg/T, respectively. Ó 2018 Elsevier B.V. All rights reserved. 1. Introduction Recent investigations have been performed on the magneto- optical properties of thin films with spinel structure (e.g. ferrites and aluminates), doped or un-doped with rare-earth (RE) ions, which can be applied for magneto-optical sensors in adopted wavelengths, optical devices and microwave communication com- ponents [1–3]. New glass materials with high magneto-optical effects are intensively studied due to their application in the domain of mag- netic field sensors and optical elements with nonreciprocal beha- viour to control polarization or for optical modulation or isolation [4]. The best-known magneto-optical effects are the Fara- day and Kerr effects. Both are related to the rotation of the polar- ization vector for light passing through or reflected from a magneto-optical material, respectively. The rotation angle, h F , of the linear polarized incident light is proportional to the passing length and magnetic induction of the material via a proportionality constant, called Verdet constant, which takes into account the intrinsic electronic properties of the material. Hence, the magneto-optical performance of materials is typically described by this Verdet constant, which is wavelength dependent and is positive for a diamagnetic material and negative for a paramag- netic material [5]. Although most glasses are weakly diamagnetic materials [6], a significant Faraday rotation of the polarization plane can be achieved when suitable paramagnetic or diamagnetic ions are incorporated in high enough concentration into the weakly diamagnetic matrix. Rare-earth-doped bulk glasses have been investigated inten- sively regarding their magnetic properties and Faraday effects [7–9]. Authors’ recent achievements in this field were related to magnetic and magneto-optical properties of RE-doped phosphate bulk glasses having application for Faraday rotators, as presented in the following three papers. By spectrometric ellipsometry on some alumino-phosphate glasses doped with La, Dy or Tb, the dia- magnetic and paramagnetic contributions to the Faraday rotation were separately analysed and specific designs for optimal active and passive elements were proposed [10]. A new sensitive method for the fast characterization of the magneto-optical properties (Faraday rotation, Verdet constant and optical homogeneity) of Dy-doped alumino-phosphate glasses is presented in [11]. Very recent investigations on magnetic and magneto-optical properties https://doi.org/10.1016/j.apsusc.2018.04.067 0169-4332/Ó 2018 Elsevier B.V. All rights reserved. ⇑ Corresponding author. E-mail address: astatin18@yahoo.com (M. Elisa). Applied Surface Science 448 (2018) 474–480 Contents lists available at ScienceDirect Applied Surface Science journal homepage: www.elsevier.com/locate/apsusc