Ion implantation of rare-earth dopants in ferromagnetic thin films

Abstract

We show that high-dose ion implantation can be used to introduce rare-earth dopants for the control of precessional dynamics in magnetic thin films. Tb and Gd ions have been implanted in Ni 81 Fe 19 through Ta masks at dosages from 1 ϫ 10 14 /cm 2 to 1 ϫ 10 15 /cm 2. Effects on dynamics are found to be similar to those contributed by cosputtered Tb and Gd dopants in Ni 81 Fe 19 ͑50 nm͒. Broadband ferromagnetic resonance measurements from 0 to 18 GHz show that adjustments in damping ␣ from 0.008 to 0.040 are fully intrinsic ͑Gilbert type͒ and roughly proportional to dose. The technique enables the creation of films with spatially modulated precessional characteristics.

Magnetic patterning by means of ion irradiation and implantation

“…Conventional doping can, for example, be employed to modify the Curie temperature of the ferromagnetic material [21,110]. In addition it has been recently demonstrated that the magnetic damping behavior can be effectively tailored by doping transition metals into the ferromagnetic films [16,21,[111][112][113]. By this means an optimized magnetization switching behavior could be achieved.…”

Study of focused-ion-beam–induced structural and compositional modifications in nanoscale bilayer systems by combined grazing incidence x ray reflectivity and fluorescence

“…18,19 The pioneering work of Chappert et al 20 on the Co=Pt magnetic systems stimulated numerous studies focused on the influence of the ion irradiation and implantation on the perpendicular magnetic anisotropy (PMA) systems. [21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36] In-plane magnetic systems, such as Permalloy (nominal composition Ni 80 Fe 20 ), have also attracted interest, and some similar studies have been conducted on those systems. [37][38][39] Energy transfer from the incident ions can cause atomic displacements of target atoms, leading to intermixing across the interface.…”

Local control of magnetic damping in ferromagnetic/non-magnetic bilayers by interfacial intermixing induced by focused ion-beam irradiation

“…These results are similar to those obtained from co-sputtering, thus indicating the effects are intrinsic to the dopants. 11 However, in the case of Cr, the damping varies according to whether the Cr is co-sputtered or ion-implanted, 10 with the biggest increase observed for implantation. With the exception of recent work on epitaxial vanadium-doped iron, 17 the addition of dopants typically increases damping.…”

“…High-energy beams are needed to ensure adequate doping, requiring either a research accelerator or a commercially available accelerator-based ion implanter. 11 High-energy heavy-ion irradiation is not usually compatible with local patterning. 15 Dopants introduced by ion-irradiation can affect the magnetic properties by introducing specific atomic species into the material, by altering the microstructure of the magnetic material (e.g., recrystallization or amorphization) or through intermixing in multilayered structures.…”

“…10 Dopants including Cr, 10 Tb, 11 Gd, 11 Ni, 12 and Fe 13 have been introduced as implanted ions. This approach can be used to introduce dopants into a localized area via lithography, 11,14 with an appropriate ion source. High-energy beams are needed to ensure adequate doping, requiring either a research accelerator or a commercially available accelerator-based ion implanter.…”