Controlling long-range skyrmion lattices using field and temperature in Fe/Gd multilayers*

To facilitate the realization of skyrmion-based devices, there is a need to design and develop materials that can host skyrmions under ambient conditions. We have fabricated thin-films of amorphous Fe/Gd multilayers that support skyrmions and skyrmion lattices at room temperature and zero applied magnetic field. By varying the film thickness and alloy composition, we can alter the balance of the dipole interactions relative to the exchange and anisotropy. Using small angle neutron scattering (SANS), we demonstrate a skyrmion lattice exists over a broad field and temperature range (including positive/negative/zero magnetic field and temperatures between 10K and 325 K, in a single film). By monitoring the temperature- and field-dependent scattering vector changes, we observe two skyrmion lattice spacing effects: increasing the field to positive saturation results in a decrease in Q suggesting an increase in the skyrmion lattice, while decreasing the field towards negative saturation results in an in Q before skyrmion lattice destabilizes.