Modulation of polarization switching barriers in Hf_0.5Zr_0.5O₂ with HfO₂ and ZrO₂ interlayers

Hf_0.5Zr_0.5O₂ (HZO) is a representative HfO₂-based ferroelectric material with strong potential for nonvolatile ferroelectric memories, where the polarization switching barrier critically governs switching dynamics and device performance. Here, first-principles calculations are employed to systematically investigate how interlayer engineering modulates the polarization switching barrier in HZO-based heterostructures. By introducing HfO₂ (HO) and ZrO₂ (ZO) interlayers, we demonstrate that the switching barrier can be either enhanced or suppressed depending on the interfacial configuration. Specifically, the HO interlayer generates an electric field aligned with the intrinsic depolarization field, leading to an increased barrier, whereas the ZO interlayers induce oppositely oriented electric fields that weaken the electrostatic constraint on oxygen displacement and reduce the barrier. This opposite behavior originates from interfacial charge redistribution and polarization dependent work function differences, which generate built-in dipole fields at the interface. These results establish a unified mechanism for interlayer modulation of polarization switching and provide guidance for the design of HZO-based ferroelectric devices.