Interfacial potential gradient modulates Dzyaloshinskii-Moriya interaction in Pt/Co/metal multilayers

Abstract

The actual mechanisms occurring at interfaces underlying the Dzyaloshinskii-Moriya interaction (DMI) remain a question in nanomagnetism. In this study, we investigate the origin of the interfacial DMI, aiming at estimating how independent the DMI contributions of the two interfaces of a FM layer are and what their relative weight in the effective DMI amplitude is. To this aim, we explore the correlation between the effective interfacial DMI and the metal properties, namely, atomic number, electronegativity, and the work function of the metal $M$. A clear linear relationship is found between the interfacial DMI and the work function difference at the $\mathrm{Co}/M$ interface. This result is strong evidence of the independent DMI contributions of the two interfaces for the chosen Co thickness(1 nm). It also suggests that the $\mathrm{Co}/\mathrm{Cu}$ interface bears no interfacial DMI. These findings can guide the optimization of the magnetic properties of future devices.