Figure 4. Robustness of the measurement principle.

(a) Spin configuration of a Néel-type skyrmion with N=1, (b) calculated CD profile, and, (c) calculated PAM. (d) Spin configuration of an anti-skyrmion with N=−1. Note that the anti-skyrmion, as well as other topological entities with negative topological numbers, are not energetically stable states. Nevertheless, our experimental principle can be applied, as shown in e,f in which the CD profile and PAM periodicity suggest the correct absolute value of the winding number. Moreover, negative winding numbers give rise to a fundamentally different PAM shape of the humps. This provides an additional way to distinguish positive from negative values of N.