Intrinsic ferromagnetism in Sm doped ZnO

Magnetic behaviours of Sm doped ZnO are studied both theoretically and experimentally. The results of first principles calculations indicate that Sm doped ZnO is ferromagnetic and the magnetic moment originates from the 4f electrons of the rare-earth element Sm. The local magnetic moments mediated by carriers in ZnO induce the ferromagnetic ordering. In addition, Sm dopants prefer uniformly distributed in ZnO matrix, suggesting possible intrinsic ferromagnetism. Experimentally, Sm doped ZnO nanoparticles were fabricated using a hydrothermal method. XRD analysis indicates that Sm has been effectively incorporated into ZnO lattice. Room temperature ferromagnetism is observed in the samples. Magnetic measurements also show that 2.5 at% Sm doped ZnO has larger saturation magnetization than 5 at% Sm doped sample. The work has shown that rare earth element doping can lead to intrinsic diluted magnetic semiconductors, which may pave ways for searching high quality diluted magnetic semiconductors using rare earth elements as dopants.