Nonlinear Topological Orbital Responses of Antiferromagnetic Skyrmions

RESUMO

Antiferromagnetic skyrmions evade the skyrmion Hall effect, but compensation suppresses their conventional topological charge Hall signal. We predict a semiclassical nonlinear topological orbital response of an isolated skyrmion in a $\mathcal{PT}$-symmetric hexagonal antiferromagnet without spin-orbit coupling. In the diffusive, weak-emergent-field regime, the spin-dependent emergent Lorentz force reshapes the carrier distribution, generating a local orbital Hall-current correction and a local orbital accumulation, both quadratic in the applied electric field. The current correction requires spin-asymmetric longitudinal scattering, whereas the accumulation survives spin-symmetric scattering. When the spin-diffusion length greatly exceeds the strip width, the current correction persists while the accumulation approaches zero. Both signals are even under electric-field reversal, odd under reversal of the skyrmion topological charge $Q$, and helicity independent within this model. These symmetries enable rectified detection and distinguish this mechanism from the $Q$-even quantum-regime topological orbital Hall effect.