Role of the substrate in the formation of chiral magnetic structures driven by the interfacial Dzyaloshinskii-Moriya interaction

We report on the experimental verification of the rotational sense of homogeneous and antiferromagnetic spin spiral structures observed on mono- and double-layer Mn thin films formed on a W(110) substrate using spin-polarized scanning tunneling microscopy. By controlling the orientation of the tip magnetization with external magnetic fields, we determined the rotational sense of the cycloidal and transverse conical spin spiral structures of the Mn/W systems and found that both exhibit a unique chirality and the same polarity for the interfacial Dzyaloshinskii-Moriya interaction (iDMI). By comparing our results with those reported for other noncollinear magnetic states formed on the same substrate, we conclude that the polarity of the iDMI, which defines the rotational sense, is predominantly determined by the substrate rather than the overlayers.