Quantum tunneling of helicity for antiferromagnetic skyrmions

We investigate quantum tunneling effects of helicity tunneling for two-dimensional topological solitons, skyrmions, for thin films of canted antiferromagnets. Using a sigma-model approach, we demonstrate that quantum tunneling between states with different helicities is possible for skyrmions stabilized by magnetic dipole interactions. We develop an analytical model incorporating an effective local term that mimics the non-local dipole interaction, enabling us to find instanton solutions describing the tunneling process. Through the path integral approach, we calculate the tunneling probability and show that the tunneling exponent can reach observable values for nanometer films of materials such as iron borate FeBO3 or hematite alpha-Fe2O3. We found a novel effect of interference of instanton paths in the presence of an external magnetic field, which manifests as oscillations in the tunnel splitting of energy levels as a function of the field. These quantum effects could be observed at experimentally accessible temperatures below tens of Kelvins. Our findings contribute to the understanding of the quantum properties of antiferromagnetic skyrmions and their potential applications in magnetic memory devices or information processing.