Ion Beam Engineering of YIG for Spin Wave based Computing Devices

Changing the effective magnetization M_eff and the Gilbert damping α_G in YIG thin films can be achieved by means of Focused Ion Beam (FIB). We utilize this technology to locally modify the spin wave dispersion relation without the need of physically removing material (e.g. etching), whereby the degree of manipulation is strongly dependent on the applied ion dose. This way, we can engineer the spin wave wavelength, phase and/or amplitude in irradiated areas, which is very useful

to fabricate complex magnonic building blocks, especially optically inspired components that require a variation of the refractive index. Low Ga⁺ ion doses can be used to increase M_eff with little to no change in magnetic damping, leading to a relative refractive index >1. Higher doses decrease M_eff and result in a strong increase of magnetic damping up until the magnetization is ‘switched off’ eventually, resulting in binary magnetization patterns.