Despite their partial ionic nature, many-layered diatomic crystals avoid internal electric polarization by forming a centrosymmetric lattice at their optimal van der Waals stacking. Here, we report a stable ferroelectric order emerging at the interface between two naturally grown flakes of hexagonal boron nitride, which are stacked together in a metastable non-centrosymmetric parallel orientation. We observe alternating domains of inverted normal polarization, caused by a lateral shift of one lattice site between the domains. Reversible polarization switching coupled to lateral sliding is achieved by scanning a biased tip above the surface. Our calculations trace the origin of the phenomenon to a subtle interplay between charge redistribution and ionic displacement and provide intuitive insights to explore the interfacial polarization and its distinctive “slidetronics” switching mechanism.

尽管具有部分离子性质，多层双原子晶体通过在其最佳范德华堆积处形成中心对称晶格来避免内部电极化。在这里，我们报告了在两个自然生长的六方氮化硼薄片之间的界面处出现了稳定的铁电有序，这些薄片以亚稳态非中心对称平行方向堆叠在一起。我们观察到反向法向偏振的交替域，这是由域之间一个晶格位置的横向移动引起的。与横向滑动耦合的可逆偏振切换是通过扫描表面上方的偏置尖端来实现的。我们的计算将这种现象的起源追溯到电荷重新分布和离子位移之间的微妙相互作用，并为探索界面极化及其独特的“滑动电子学”切换机制提供了直观的见解。