Magneto-optic gradient effect in domain-wall images: At the crossroads of magneto-optics and micromagnetics

An anomalous symmetry of magneto-optical images of ferromagnetic domain walls was reported by Schaefer and Hubert [Phys. Status Solidi A 118, 271 (1990)] and interpreted in terms of light amplitudes proportional to the magnetization gradient. We present analytic and numerical calculations supporting such proportionality under additional conditions implied by classical rules of micromagnetics and address some objections presented by Banno [Phys. Rev. A 77, 033818 (2008)] against such proportionality.