Ferromagnetic ordering and metallic-like conductivity in sputtered SnNx films

Polycrystalline SnNx films were fabricated by reactive sputtering with various substrate temperatures. The film has a hexagonal tin-rich structure and decomposition temperature is above 500 °C. The band-gap enlarged to 3.10 eV due to the complex defects and the conductivity of the films shows metallic-like behavior, which has the opposite variation trend with ferromagnetism as the substrate temperature changes. The origin of ferromagnetism may be from the intrinsic point defects, which result in a net moment by unpaired spin electrons. The feeble coercivity with no obvious magnetocrystalline anisotropy suggests that the magnetism in our samples is not a bulk effect, and it distributes unevenly in the grain boundaries or interfaces. Furthermore, thermal decomposition also has significant influence on the magnetic and transport properties.