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Magnetic and optical properties of Mn-doped SnO2 films S.Sujatha Lekshmy, Anitha V.S, K. Joy* Thin film Lab, Post Graduate and Research Department of Physics, Mar Ivanios College, Thiruvananthapuram 695015. *Corresponding author e-mail: [email protected] ABSTRACT Magnetic nanoparticles have drawn much attention due to their potential in magnetic recording as well as many biological and medical applications such as magnetic separation, hyperthermia treatment, magnetic resonance contrast enhancement and drug delivery. The magnetic fields generated by these nanoparticles can be used for diagnostics in Magnetic Resonance Imaging (MRI) etc. Manganese doped tin dioxide (SnO2:Mn) possess interesting physical and chemical properties. The physical and chemical properties of the particles themselves like the size, shape, crystallinity and composition, will control the magnetic properties and response of the particles to magnetic fields. Our work is rooted to control the properties of the particles as well as tailor their magnetic properties for specific applications. In this study, SnO2: Mn films with different Mn doping concentrations (0-3 mol%) were deposited on the glass substrates by sol-gel dip coating technique. XRD patterns shows tetragonal structure for all the SnO2:Mn films and crystallite size decreased as Mn doping concentration increased from 0 - 3 mol%. The magnetic property shows that pure SnO2 film is diamagnetic and 1- 3 mol% SnO2:Mn films posses room temperature ferromagnetism. The optical properties of the films revealed that transmittance of the films decreased with increase in Mn doping concentration. The optical energy band gap values (3.55 eV-3.71 eV) increased with the increase in Mn doping concentrations. Such SnO2:Mn films with structural, optical and magnetic properties can be used as dilute magnetic semiconductors. Keywords: Tin oxide, Thin films, Sol gel processing, X-ray diffraction, Magnetic properties 1. INTRODUCTION The rapidly developing field of spin electronics requires a semiconducting room temperature ferromagnet for incorporation in spin-electronic devices. Among the necessary requirements in order to have a spintronic device , is the need of an efficient electrical injection of spin-polarized carriers (spin injection) into the semiconductor. Tin dioxide (SnO2) is an attractive semiconductor for the fabrication of diluted magnetic semiconductors (DMS) because of its excellent optical transparency, native oxygen vacancies and high carrier density . In the quest for materials which involve both the charge and spin of electrons in a single substance, studies have also paid considerable attention on SnO2-based DMS realized through transition-metal (TM) doping. During the past few years, the DMS in which a small fraction of atoms/ions is magnetic, have attracted considerable attention from both the fundamental as well as the application points of view. This is primarily due to the possibility that, in these DMSs, the two degrees of freedom (spin and charge) can be independently tuned to re