Fig. 3: Polarization-electric field (P_2D -E) hysteresis loops.

a The difference of Hall carrier density \({n}_{\text{H}}\) between the forward and backward sweeps of external electric field \(E\) at each fixed carrier density \({n}_{\text{total}}\). b Two-dimensional polarization \({P}_{2\text{D}}\) as a function of \(E\) measured by sweeping \(E\) sequentially in the direction denoted by the arrows at fixed \({n}_{\text{total}}=0\). c Scan-range dependent \({P}_{2\text{D}}-E\) hysteresis loops measured by the same method as that in (b). The remanent polarization \({P}_{\text{r}}\) and saturation polarization \({P}_{\text{s}}\) are extracted according to the marks in the plots. d Summary of \({P}_{\text{r}}\) and \({P}_{\text{s}}\) as a function of scan range \({\left|E\right|}_{\max }\). e Schematic of charge polarization and saturation at each process marked in (b). The red wavy lines illustrate the moiré potential. The green (red) ball denotes hole (electron). The arrows illustrate the injection (or extraction) process of charge carriers at top and bottom interfaces controlled by \({V}_{\text{t}}\) and \({V}_{\text{b}}\), respectively. The black wavy lines in Process iii and viii denote the recombination of electrons and holes. Process i, iv, v, and vi are GSAS regions. Process ii, iii, vii, and viii are the normal dual-gating regions. All the data in (b) and (c) were measured at fixed \({n}_{\text{total}}=0\). The sharp peaks near \({P}_{2\text{D}}=0\) in (b, c) are due to the measured \({R}_{{xy}}\to 0\) when passing through CNP.