Mechanisms and Control of Inter-Skyrmion Attractions

To commercialize stable, highly-integrated, and low-power-consuming magnetic memories of skyrmions, stable control of their motion are crucial. The key is to manipulate the inter-skyrmion interactions. However, conventional circular skyrmions have only isotropic repulsion and the mechanism of inducing attraction has been unclear. We theoretically find two such mechanisms, distortion of skyrmion shape and formation of magnetic domains. Remarkably, the latter induces strong attraction which can be tuned by two orders of magnitude, by tilting the external magnetic field.