Antiferroelectric thin films embedded with ferroelectric switching loop for giant negative electrocaloric effect

The ferroics combine the single-hysteresis loop of ferroelectrics with the double-hysteresis loop of antiferroelectrics to form multiple hysteresis loops, which could substantially advance energy storage, electrocaloric cooling, and nonvolatile multistate memory technologies. However, the intentional stabilization of intermediate states that bridge the nonvolatility of ferroelectrics and the field-induced phase transition behavior of antiferroelectrics remains a fundamental challenge. Here, we propose a strategy for preparing lead zirconate (PbZrO₃) thin film at low temperature, introducing a stable ferrielectric phase within the antiferroelectric to achieve triple-hysteresis loop under large electric fields. Microstructural features reveal that this behavior is attributable to the presence of Pb_Zr antisite defects acting as seeds for polar order, which induce the distinctive triple (↑↑↓) dipole modulation period configuration. To demonstrate the application potential, we evaluated the electrocaloric effect of triple-hysteresis PbZrO₃ thin film based on Maxwell's relations, the predicted temperature change ΔT can reach -23.76 kelvins, which is ~600% enhancement compared to double-hysteresis PbZrO₃ antiferroelectric thin films. These findings establish a design paradigm for embedding stable ferroelectric switching within antiferroelectrics, which may unlock opportunities for developing high-density energy storage, nonvolatile multistate memory, and highly efficient switching devices.