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.