Above-room-temperature ferromagnetic $Ni2+$-doped $ZnO$ thin films prepared from colloidal diluted magnetic semiconductor quantum dots

We report the preparation of spin-coated nickel-doped zinc oxide nanocrystalline thin films using high-quality colloidal diluted magnetic semiconductor (DMS) quantum dots as solution precursors. These films show robust ferromagnetism with Curie temperatures above $350K$ and $300K$ saturation moments up to $0.1Bohr$ magnetons per nickel. These results demonstrate a step toward the use of colloidal zero-dimensional DMS nanocrystals as building blocks for the bottom-up construction of more complex ferromagnetic semiconductor nanostructures.