Extended Data Fig. 1: Kernel filter for subtracting the electric field signal component.

Schematic illustration of the kernel filter. In this filter, DPC signals of four nearby points (denoted 2, 4, 6 and 8) are averaged and then subtracted from that of the centre point (denoted 0). This operation is illustrated in the right schematic. The numbers in the schematic show the weighting factors at each point in this kernel filter. The distance between the points corresponds to the distance between the Fe atomic dumbbells. This filter subtracts the electric field component and reinforces the magnetic field component at the centre Fe atomic columns.