Computational-Guided Search for Ultrasmall Skyrmions in Ferrimagnets*

Magnetic skyrmions are topologically protected spin textures. They can potentially improve density and energy efficiency in memory and logic devices. With the immense material's space, it could take years to experimentally explore all the possible materials for skyrmions' device application. To guide experiments, we employ computational models to identify several materials for stabilizing ultrasmall skyrmions at room temperature. One of the more promising candidates is amorphous rare-earth-transition-metal ferrimagnet. Our atomistic stochastic Landau-Liftshitz-Gilbert (LLG) model has revealed that Néel skyrmions, with a diameter of 10 nm or less, are stable in 5 nm thick GdFe and GdCo at room temperature. Following this guidance, we have fabricated GdCo samples and controlled the Dzyaloshinskii-Moriya interaction (DMI) through tuning the interfacial layers. Results from these samples are used as feedbacks to refine our computational models. Using this computational-guided approach, the time needed to explore promising materials for skyrmions-based devices will be vastly reduced.