Dual-synthetic magnetic force microscopy tip and its imaging performance

A multilayer structure magnetic force microscopy (MFM) tip coated with antiferromagnet/ferromagnet/Ru/ferromagnet/Ru/ferromagnet/antiferromagnet on one side of the tip has been fabricated and evaluated. The ferromagnet used was CoFe. The central CoFe layer is antiferromagnetically (AFM) coupled with the two-side CoFe layers via ultra-thin Ru layers through optimizing the Ru layer thickness. The strong antiferromagnetic coupling between the CoFe layers leads to a more stable magnetization configuration and confined tip stray field as compared to that of conventional single-layer coated tips. The former improves the signal-to-noise ratio of the detected signals and the latter leads to an improvement of spatial resolution. The performance of this kind of tip has been evaluated by imaging magnetic patterns and comparing them with the images taken by both ferromagnetically coupled multilayer tips and commercial tips. Micromagnetic modeling has been performed to gain an understanding of the experimental results.