Magnetism in Ar-implanted ZnO

Abstract

ZnO single crystals were implanted with Ar ions with an energy of 100 keV and different fluences. Ferromagnetic behaviour is observed at room temperature after implantation. This behaviour is suppressed after consecutive annealings at 400 and 500 °C. Although trace transition metal impurities have been identified in the virgin samples, it is shown that they cannot account for the observed magnetic behaviour that is assigned to the presence of implantation-induced lattice defects.

Non‐DMS related ferromagnetism in transition metal doped zinc oxide

“…Uncompensated surface spins are nearly ruled out as the only source for the observed room-temperature ferromagnetism. Defect induced ferromagnetism, as in our case, has been observed in Ar + irradiated ZnO [56]. There is only limited potential for application of defect induced ferromagnetism.…”

“…In the paper of Borges et al [56], ferromagnetic properties have been introduced in ZnO by means of Ar ion implantation. Although spurious elements could be detected inside the crystals, the authors could assign the ferromagnetic properties to defects induced by the implantation.…”

Room temperature ferromagnetism in carbon-implanted ZnO

“…260 nm thick ZnO films were grown from a ZnO ceramic target on 10 The TRIM code was used to simulate the depth dependent distribution of implanted C in the ZnO films [14]. In order to obtain a box-like C distribution in the ZnO films, four different energies with different fluences of C were implanted in the same film at room temperature.…”

“…The 4 at. % C-implanted sample was annealed in air for 2 hours at 400 o C [10]. After annealing, the sample magnetization is not significantly changed, but the coercivity is increased from ~100 Oe to ~250 Oe.…”

“…After annealing, the sample magnetization is not significantly changed, but the coercivity is increased from ~100 Oe to ~250 Oe. Thus, we can exclude the purely defect-induced ferromagnetism, since in such case the saturation magnetization should significantly drop with post-annealing [10].…”