The topological magnetoelectric effect (TME) in three-dimensional topological insulators (TIs), described by $\mathrm{\Delta }P=(e^2/2h)N_{\text{Ch}}^{(2)}\mathrm{\Delta }B$, serves as a condensed-matter realization of the four-dimensional quantum Hall effect (4D QHE). In dual-gate axion insulator devices, the TME-induced polarization yields a current $I_{\mathrm{TME}}\propto (C_{\text{total}}/C_{\mathrm{S}})Q_{4\mathrm{D}-\mathrm{QHE}}$, where the signal is suppressed by the capacitance ratio $C_{\text{total}}/C_{\mathrm{S}}$. Here we propose an active compensation scheme that introduces a tunable negative capacitance $C_{\mathrm{comp}}\approx -C_{\mathrm{gate}}$ into the gate line, effectively canceling the gate dielectric capacitance and driving $C_{\text{total}}/C_{\mathrm{S}}\to 1$. We validate the method using a quantum anomalous Hall (QAH) device, which shares the same surface-state physics as the axion insulator but permits direct charge measurement via a single gate, recovering over 95% of the quantized charge signal from an initially half-attenuated state. This compensation method provides a robust means of resolving minute TME signals, offering a pathway toward direct measurements of the 4D QHE.

Close

PrevNext

View figure in article

• Topological insulators
• Topological materials