A study of chiral magnetic stripe domains within an in-plane virtual magnetic field using SPLEEM

Stripe domains form in magnetic thin films at the spin reorientation transition. Different from the typical Bloch type domain walls (DW), it was found recently that Dzyaloshinskii--Moriya interaction (DMI) could lead to chiral N\'{e}el type DMs in the stripe domain phase. While the application of an out-of-plane magnetic field is known to break the stripes into skyrmions, it is unclear how the chiral stripe phase would respond to an in-plane magnetic field? Here we report an experimental study on Fe/Ni/Cu/Co/Cu(001) system using spin-polarized low-energy electron microscopy (SPLEEM). In this system, the Fe/Ni layer exhibits stripe domains with chiral N\'{e}el type DMs and its interlayer coupling to Co across the Cu spacer layer serves as an in-plane virtual magnetic field whose strength can be tuned by changing the Cu spacer layer thickness. We find the in-plane field aligns the stripes parallel to the field direction. Increasing the in-plane field strength gradually changes the N\'{e}el type DWs into Bloch type DWs. However, it is surprising the adjacent N\'{e}el DWs behave asymmetrically in-response to the in-plane magnetic field, suggesting a topological effect in switching the chiral N\'{e}el DWs to the non-chiral Bloch DWs.