Skidmore Chloe H, Spurling R Jackson, Hayden John, Baksa Steven M, Behrendt Drew, Goodling Devin, Nordlander Joshua L, Suceava Albert, Casamento Joseph, Akkopru-Akgun Betul, Calderon Sebastian, Dabo Ismaila, Gopalan Venkatraman, Kelley Kyle P, Rappe Andrew M, Trolier-McKinstry Susan, Dickey Elizabeth C, Maria Jon-Paul
Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA, USA.
Department of Chemistry, The University of Pennsylvania, Philadelphia, PA, USA.
Nature. 2025 Jan;637(8046):574-579. doi: 10.1038/s41586-024-08295-y. Epub 2025 Jan 8.
Proximity ferroelectricity is an interface-associated phenomenon in electric-field-driven polarization reversal in a non-ferroelectric polar material induced by one or more adjacent ferroelectric materials. Here we report proximity ferroelectricity in wurtzite ferroelectric heterostructures. In the present case, the non-ferroelectric layers are AlN and ZnO, whereas the ferroelectric layers are AlBN, AlScN and ZnMgO. The layered structures include nitride-nitride, oxide-oxide and nitride-oxide stacks that feature two-layer (asymmetric) and three-layer (symmetric) configurations. Ferroelectric switching in both layers is validated by multimodal characterization methods, including polarization hysteresis, anisotropic chemical etching, second harmonic generation, piezo response force microscopy, electromechanical testing and atomic resolution polarization orientation imaging in real space by scanning transmission electron microscopy. We present a physical switching model in which antipolar nuclei originate in the ferroelectric layer and propagate towards the internal non-ferroelectric interface. The domain wall leading edge produces elastic and electric fields that extend beyond the interface at close proximity, reducing the switching barrier in the non-ferroelectric layer, and allowing complete domain propagation without breakdown. Density functional theory calculations of polymorph energies, reversal barriers and domain wall energies support this model. Proximity ferroelectricity enables polarization reversal in wurtzites without the chemical or structural disorder that accompanies elemental substitution, opening new questions and opportunities regarding interface-based ferroelectricity.
近邻铁电性是一种与界面相关的现象，存在于由一种或多种相邻铁电材料诱导的非铁电极性材料的电场驱动极化反转过程中。在此，我们报道纤锌矿型铁电异质结构中的近邻铁电性。在当前情况下，非铁电层为AlN和ZnO，而铁电层为AlBN、AlScN和ZnMgO。这些层状结构包括氮化物-氮化物、氧化物-氧化物和氮化物-氧化物堆叠，具有双层（不对称）和三层（对称）构型。通过多模态表征方法验证了两层中的铁电开关特性，这些方法包括极化滞后、各向异性化学蚀刻、二次谐波产生、压电响应力显微镜、机电测试以及通过扫描透射电子显微镜在实空间进行的原子分辨率极化取向成像。我们提出了一个物理开关模型，其中反极核起源于铁电层并向内部非铁电界面传播。畴壁前沿产生的弹性场和电场在紧邻界面处延伸到界面之外，降低了非铁电层中的开关势垒，并允许畴完全传播而不会击穿。多晶型能量、反转势垒和畴壁能量的密度泛函理论计算支持了这一模型。近邻铁电性使得纤锌矿型材料能够实现极化反转，而无需伴随元素取代的化学或结构无序，这为基于界面的铁电性带来了新的问题和机遇。
