Ferromagnetism in Mn- and Co-implanted ZnO nanorods

ZnO nanorods with typical lengths and diameters of /spl sim/2 /spl mu/m and 15-30 nm, respectively, were grown on Ag-coated Si substrate by catalyst-driven Molecular Beam Epitaxy and subsequently implanted with Mn/sup +/ or Co/sup +/ ions of dose ranging from 1-5/spl times/10/sup 16/ cm/sup -2/. The samples were then annealed at 700/spl deg/C for 5 minutes. The structural properties were unaffected, but they exhibited ferromagnetism that persisted up to temperatures of 225-300 K. Coersive fields were /spl les/100 Oe even at 10 K. The results are similar to those obtained for implantation of Mn/sup +/ and Co/sup +/ ions in bulk, single-crystal ZnO, indicating the promise of nanorods for nanoscale spintronics.