Exchange-stiffness measurement scheme based on domain-wall chirality transition

Abstract

Herein, we propose an experimental scheme to determine the strength of the Heisenberg exchange interaction in ultrathin magnetic films. In this scheme, the chirality transition between the Bloch- and Néel-type domain walls is analyzed under an in-plane magnetic field. Subsequently, the exchange stiffness constant is estimated based on the strength of the magnetic field for chirality transitions, as proposed by an analytical theory pertaining to chirality transitions, and confirmed based on micromagnetic prediction. Using the magneto-optical Kerr effect with high sensitivity on surface atomic layers, the present scheme is applicable to ultrathin magnetic films down to a few atomic layers, whose sensitivity is well below the lowest sensitivity limit of conventional measurement schemes. Hence, the present scheme is useful for extending the experimental range to investigate the exchange stiffness of few-atomic-layer-thick magnetic films.