Sss mfmr

Films were grown by magnetron sputtering at a base pressure below 1 × 10⁻⁸ Torr. The sample structure was substrate/Ta(2)/Pt(3)/[Co(1.95)/Gd(1.2)/Pt(3)]₇ (with thicknesses given in parentheses in nanometres). The hysteresis loop measured by Polar MOKE at room temperature is shown in supplementary Fig. 2a.
L-TEM measurements with a tilting angle of 10° were conducted to observe the magnetic structures and confirm the skyrmion type in the multilayer structure at room temperature. The sample deposited on a 50-nm-thick silicon nitride membrane (CleanSiN) was used for L-TEM measurements. As shown in supplementary Fig. 2b, the magnetization reversal process, and Néel-type skyrmions in the Pt/Co/Gd multilayers are confirmed^{35 (link),46 (link)}.
MFM measurements were conducted with the MFP-3D Infinity atomic force microscope, using the high-resolution and low-moment magnetic probe, SSS-MFMR (Nanosensors), with a lifted height of 30 nm.

Room temperature MFM experiments were carried out using a Veeco Dimension 3100 Scanning Probe Microscope. The MFM tips used (Nanosensors SSS-MFMR) were ≈30 nm in diameter, with low coercivity (≈12 mT) and ultralow magnetic moment (≈80 emu/cc). Samples were initially saturated in the out of plane (OP) direction using fields up to H = −0.5 T. The measurements were performed in OP fields starting from H = 0 and incrementally approaching H = +H_S, with a typical tip height of 20 nm. The field evolution of the spin textures is presented in Section 1 of the Supplementary Information. Low T (5–200 K) MFM imaging is carried out using a cryogenic frequency-modulated MFM system^{9 (link)}. We used two commercial probes by Team Nanotec, model ML3 (35–40 nm Co alloy coating), with f₀ ≈ 75 kHz and k₀ ≈ 1 N/m. The sample was first stabilized at a given temperature and then magnetized in the OP direction by applying H > H_S. After saturation, MFM images were acquired at various field values as H was swept from −H_S to +H_S. The details of the MFM image analysis are reported in our earlier reports^{5 (link),9 (link),30 (link)}.