Fig. 3: Atomic structure of CuVP2S6 and the in-situ process.
a Low-magnification image of the CuVP2S6 sample, showing regular dissociation surfaces. b Atomic structure of CuVP2S6 in [001] direction with relative atomic model. The red, blue, mauve, and yellow dots represent Cu, V, P, and S atoms, respectively. c Atomic structure of CuVP2S6 in [010] direction with relative atomic model. d Atomic model illustrates the Cu ion migration process. e Schematic of low-dose e-beam irradiation on the CuVP2S6. f Atomic structures of the irradiation process at 2 s, 4 s, and 6 s. The yellow rectangle and array show the Cu ion migration direction from right to left, and the blue rectangle and array show the Cu ion migration direction from left to right. g Schematic diagram of the in-situ STEM system equipped with electrical biasing capabilities h HAADF-STEM image of a CuVP2S6 sample under +9 V bias, showing leftward polarization reconfiguration. Yellow arrows and dashed boxes indicate the migration trajectories of Cu ions toward the left. i HAADF-STEM image of the pristine CuVP2S6 sample (zero bias), displaying the equilibrium distribution of Cu ions within the van der Waals layered structure. j HAADF-STEM image of the CuVP2S6 sample under −9 V bias, demonstrating rightward polarization reversal. Blue arrows and boxes highlight the coordinated displacement of Cu ions toward the right, consistent with field-driven ferroelectric switching dynamics.
