Structure and magnetism of V-doped SnO₂ thin films: Effect of the substrate

We report on the structure and magnetism of V-doped SnO₂ thin films grown by pulsed laser deposition. The structure and magnetic properties of the films strongly depend on the substrates on which the films are grown. Films grown on Al₂O₃ substrates are single crystalline and show anisotropic in-plane magnetic moments, while films grown on Si substrates are nanocrystalline and show no anisotropy. Compared with that of single-crystalline films, the magnetic moment of nanocrystalline films is higher at low V concentration, decreases more quickly as the V concentration increases, and is more sensitive to vacuum annealing. Our results suggest important roles for spin-orbit coupling and defects in the magnetism of diluted magnetic oxides.