Credit: Image courtesy of Weida Wu
Left: Piezo-response force microscopy image of ferroelectric domains in hexagonal erbium manganite. Image size: 16 x 16 μm2. Blue (red) color denotes domains with up (down) electric polarization. Right: Magnetoelectric force microscopy image showing a map of electric field induced magnetic response of the same area as that in the left panel. Dark (bright) contrast denotes positive (negative) magnetic response. The one-to-one correspondence between these two images confirms that the sign of electric-induced magnetic response is determined by the polarization state.