Fig. 1: Comparison of piezoresponse due to domains and domain walls in CuInP₂Se₆ and Cu_0.4In_1.2P₂S₆.

CuInP₂Se₆ surfaces were measured at 140 K in ultrahigh vacuum and that of CuInP₂S₆—at room temperature in controlled environment: a, b piezoresponse signals Acos(θ) (where A is the amplitude and θ the phase of piezoresponse)—revealing at least three distinct magnitudes of piezoresponse for both materials, and c, d line-profiles of piezoresponse along the white dashed lines, crossing domain boundaries in a, b, respectively. Orange arrows point to the regions of the domain walls.