Magnetic heterostructures Magnetism in Co-implanted ZnO films

The first Co-implanted ZnO films have been grown and their structural and magnetic properties were determined. Diluted magnetic semiconductors (DMS) have attracted much interest in recent years because of the possibility involving charge and spin degrees of freedom in a single substance. It is expected to establish semiconductor spin electronics (spintronics) as a practical technology based on such functional materials [1]. Therefore, there has been strong encouragement to synthesize a ferro-magnetic DMS whose Curie temperature (TC) is much higher than room temperature. Dietl et al. [2] suggested, by a mean field theory, ZnO and GaN as candidates having a high TC and a large magnetization. Therefore, an investigation on the feasibility of ZnO-based DMSs is of great interest. For the growth of ZnO we used epi-polished single-crystalline oriented sapphire wafers. Prior to the ZnO deposition the substrates were annealed at 500oC for 3 h in the high-vacuum sputtering chamber with a base pressure of 1 · 10−7 mbar and etched for 10 min with an Ar ion beam. RF-sputtering was carried out in an atmosphere of 5 · 10−3 mbar pure Ar (99.999 %) at 500oC. The nominal thicknesses of the sputter deposited ZnO films were in the range of 200 Å. In order t