Ferromagnetism in Mn- and Co-implanted ZnO nanorods

ZnO nanorods with diameters of 15–30 nm were grown on Ag-coated Si substrates by catalyst-driven molecular beam epitaxy and then implanted with ${\mathrm{Mn}}^{+}$ or ${\mathrm{Co}}^{+}$ ions to doses of ${\text{1–5×10}}^{16}\hspace{0.17em}{\mathrm{cm}}^{\text{−2}}.$ After subsequent annealing at 700 °C for 5 min, the structural properties of the nanorods were unaffected, but they exhibited ferromagnetism that persisted to temperatures of 225–300 K. The coercive fields were ⩽100 Oe even at 10 K. The results are similar to those obtained for implantation of ${\mathrm{Mn}}^{+}$ or ${\mathrm{Co}}^{+}$ ions in bulk single-crystal ZnO and indicate promise for nanorods for nanoscale spintronic applications.