Co-doped SrSnO3 epitaxial thin films on MgO with tunable band gap and room-temperature ferromagnetism

Abstract Co doped SrSnO 3 films (SrSn 1-x Co x O 3 ( 0 ≤ x ≤ 1 . 0 ), i.e., SSCO) was grown on MgO single crystal substrates by pulsed laser deposition method. Effects of the Co doping content on the crystallinity, microstructure, optical and magnetic properties were examined. For all the films the epitaxial growth along (002) plane was realized, and the lattice constant dropped from 4.065 A to 3.854 A with the ‘x’ value changing from 0 to 1.0. The Co doping promoted the growth of grains and the RMS roughness of the film increased from 3.17 nm to 9.44 nm. With the increase of the Co doping level, the optical transmittance decreased from 95% to 28% at 500 nm, and the band gap varied from 4.51 eV to 3.16 eV. All the films exhibited the room temperature ferromagnetism, and the highest saturated magnetization of 61 emu/cm 3 and the coercive force of 0.018 T were realized in the SSCO (x = 1.0) film.