Characterization of trilayers for stabilization of Skyrmions in room temperature

Magnetic skyrmions are promising candidates for spintronic and memory devices, but their stabilization at room temperature remains challenging because Dzyaloshinskii–Moriya, magnetic anisotropy and Zeeman energies must be finely balanced to overcome thermal fluctuations. We employed an anisotropy-gradient approach to build heterostructures with gradual spin reorientation from in-plane to out-of-plane in CoCr films of different thicknesses deposited on Si substrates. By tuning the CoCr thickness (t_CoCr), spin direction can be controlled, and applied fields may promote cocoon-like spin textures. Using magnetron sputtering, we fabricated Si/Ta/Pt/CoCr(t_CoCr)/Ta/Pt and Si/Ta/Pt/CoCr(t_CoCr)/Cu/Pt heterostructures with t_CoCr = 2-14 nm. Structural, thickness and roughness properties were analyzed by X-ray diffraction and reflectivity, showing that CoCr grows in a face-centered cubic structure with near-nominal thickness; Ta buffers produced smoother films than Cu, while heterostructures showed cumulative roughness. Magnetization M(H) loops measured under in-plane and out-of-plane fields revealed thickness-dependent spin reorientation. In graded multilayers Si/Ta/[Pt/CoCr(t_CoCr)/Ta]₅/Pt and Si/Ta/[Pt/CoCr(t_CoCr)/Cu]₅/Pt with thickness sequences 4-5-6-5-4, 8-7-6-7-8 and 10-8-6-8-10 nm, the magnetic anisotropy evolution was investigated. M(H) loops displayed wasp-waist shapes, indirectly suggesting skyrmion structures, though deeper analysis is required.