Fig. 2

Real-space visualization of the lattice trimerization amplitude Q across the ferroelectric phase transition. a–c HAADF-STEM images of a 10-unit-cell YMnO₃ thin film overlayed with the spatial distribution of the trimerization amplitude Q at the temperatures T = 448 K (a), 473 K (b), and 498 K (c), with T_Q = 498 K as phase transition temperature. d–f Histogram plots showing the number of occurences N of the Q and φ values (defined in Fig. 1a) for each temperature in a–c, respectively.