Chirality-induced effective field in Pt/Co/MgO system with spatial anisotropy-modulation

Abstract

In a perpendicularly magnetized (PM) material with the interfacial Dzyaloshinskii–Moriya interaction (iDMI), a chirality-induced effective magnetic field (EMF) acts on a magnetic domain wall, which is a naturally formed in-plane magnetized (IM) region sandwiched by perpendicular (PM) regions. In this study, we artificially created a Pt/Co/MgO system with the regions exhibiting different anisotropy, that is, IM and PM regions, and the chirality-induced EMF at the PM/IM boundary was investigated using it. The EMF in the IM region was probed using magnetoresistance (MR) measurements. When the field was applied orthogonally to the wire, a unidirectional shift of the MR curve was observed, indicating that the EMF exists in the IM region. The dependence of the EMF on the width of the IM region suggests that the EMF acts dominantly on the magnetization near the PM/IM boundary. Moreover, the sign of the shift is reversed with reversing the PM direction. The sign and magnitude of the EMF observed in this study suggest that the EMF in the present system is caused by iDMI.