Controlling and patterning the effective magnetization in Y3Fe5O12 thin films using ion irradiation

Abstract

We report an approach to controlling the effective magnetization (Meff), a combination of the saturation magnetization and uniaxial anisotropy, of the ferrimagnet Y3Fe5O12 (YIG) using different species of ions: He+ and Ga+. The effective magnetization can be tuned as a function of the fluence, with He + providing the largest effect. We quantified the change in effective magnetization through an angular dependence of the ferromagnetic resonance before and after irradiation. Increases in 4πMeff were observed to be as much as 400 G with only a 15% increase in Gilbert damping, α (from 8.2e-4 to 9.4e-4). This result was combined with a method for accurate ion pattering, a focused ion beam, providing a mechanism for shaping the magnetic environment with submicron precision. We observe resonance modes localized by ion patterning of micron-sized dots, whose resonances match well with micromagnetic simulations. This technique offers a flexible tool for precision nanoscale control and characterization of the magnetic properties of YIG.

Spin-Wave Optics in YIG by Ion-Beam Irradiation

“…In our work, we first demonstrate the effect of FIB irradiation on spin waves in YIG for plane-wave propagation and characterize the dependence of magnonic wavelength on FIB dose, obtaining n. Lenses and diffraction gratings are designed with a binary irradiation pattern -in a similar fashion to elementary optical devices, where light propagates either through glasses or vacuum. We find that the effect of FIB irradiation on YIG films can be modeled precisely enough by assuming an effective magnetization (M eff ) value that varies with the FIB dose, which is in agreement with the findings in other work 14 . The spatially varying M eff results in a spatially varying dispersion relation for the film, which, in turn, may be understood as a spatially varying index of refraction n. As a consequence, FIB irradiation allows the realization of (almost) arbitrary two-dimensional n profiles.…”

Skyrmions Under Control—FIB Irradiation as a Versatile Tool for Skyrmion Circuits

“…An increase of M eff , is often attributed to stronger intermixing of the magnetic layer and an attributed reduction of the saturation magnetization. [ 23 ] Beyond the effects on the uniaxial anisotropy and the saturation magnetization, for strong intermixing also a reduction of the effective exchange constant can be considered. Surprisingly, the parameter changes due to irradiation are very similar to that of annealing, within the measurement error range.…”

Experimental demonstration of a concave grating for spin waves in the Rowland arrangement

“…Sub-micron resolution patterning can easily be achieved (possibly down to 100 nm in our facility). A similar method was recently described in 19 , where comparably lower doses were used to change magnetic properties of YIG on film level. Here, we deliberately used higher doses to drastically reduce the saturation magnetization of YIG locally, to create a region which inhibits spin-wave transmission.…”