Fig. 3. Demonstration of antiferroelectric negative capacitance.

a Experimental setup of the pulsed charge-voltage measurements on the dielectric-antiferroelectric heterostructure. V_in, V_DE-AFE, R and I are the applied voltage pulse, the voltage across the DE-AFE capacitor, the series resistor (5.6 kΩ) and the current through R, respectively. The waveforms of V_in and V_DE-AFE were measured using an oscilloscope at different amplitudes of the V_in pulse. b Transient waveforms of V_in, V_DE-AFE, I and integrated charge for a HfO₂(8 nm)/Al₂O₃(~ 1 nm)/ZrO₂(10 nm) capacitor. c Maximum charge Q_max, residual charge Q_res, and reversibly stored charge ΔQ as functions of maximum voltage across the DE-AFE capacitor V_a measured from the waveforms shown in b. d Polarization P as a function of extracted electric field E_a across the ZrO₂ layer in a HfO₂(8 nm)/Al₂O₃(~ 1 nm)/ZrO₂ (10 nm) heterostructure capacitor. The P–E_a characteristics of an equivalent stand-alone ZrO₂ capacitor measured on a conventional ferroelectric tester is also shown for comparison in the background. The negative capacitance regions (C_AFE < 0) in the P–E_a curve correspond to the capacitance enhancement regions in the ΔQ-V_a curve shown in c. e Extracted energy landscape of ZrO₂. Second derivative of the free energy G with respect to P based on a polynomial fit is shown below.