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

Ordered magnetic skyrmion lattices presents a playground of new and interesting physics to explore. This opportunity is provided by the topological nature of the skyrmion. We have recently fabricated thin-films of amorphous Fe and Gd multilayers that support skyrmions and skyrmion lattices at room temperature and zero applied magnetic field. These skyrmions are stabilized by dipolar interactions, rather than the Dzyaloshinskii–Moriya interaction (DMI). By varying the film thickness and alloy composition we can alter the dipole interactions relative to the exchange and anisotropy and thus control the skyrmion size, pitch, and stability. Using small angle neutron scattering (SANS), we demonstrated that once formed these dipole skyrmions are stable over a large field and temperature range including zero field and room temperature. We observe temperature and field dependent changes in the scattering vector (Q) for peak scattering related to the skyrmion lattice spacing. The origin of this change has led us to identify a key requirement necessary for the range of stability that we have observed in these amorphous thin films.