Low field room temperature magnetism and band gap modifications in Sm doped SnO2

Abstract

The structural, optical and magnetic properties of pure and Sm doped SnO2 nanoparticles synthesized in aqueous solution by a low cost chemical co-precipitation method without using any stabilizing agent have been reported. X-ray diffraction analysis reveals that the crystallite size of SnO2 decreases with the increase of Sm doping into the SnO2 matrix. The calculated value of optical band gap of undoped SnO2 nanoparticles is calculated to be 2.65 eV and it anomalously increases with the increase of Sm3+ concentration. The band gap of undoped SnO2 nanoparticles is found to be lower than those reported for bulk SnO2 (3.6 eV) that may be due to the presence of defects, oxygen vacancies and non-stoichiometry of SnO2 nanoparticles. All the undoped and Sm doped SnO2 nanoparticles show weak room temperature magnetism in the range of applied low magnetic field region of 2000 Oe due to the presence of defects and oxygen vacancies. All the samples exhibit negative magnetic susceptibility for the applied magnetic field higher than 2000 Oe. The strong optical absorption with weak magnetic properties at room temperature may serve the SnO2 nanomaterials as a potential candidate for many DMS, spintronics, and optoelectronics based applications.