Anomalous ferroelectricity and double-negative effects in bilayer hexagonal boron nitride
Wen Jiang, Chang Liu, Xiaonan Ma, Xing Yu, Shunbo Hu, Xi Li, Lee A. Burton, Yu Liu, Yangyang Chen, Pan Guo, Xiangyang Kong, L. Bellaïche, Wei Ren
Abstract
Recently, the presence of an out-of-plane ferroelectric polarization was experimentally confirmed in bilayer two-dimensional (2D) hexagonal boron nitride (h-BN). In this work, we employ first-principles computations to reveal that (i) such slidetronic ferroelectricity is electronic in nature and arises from in-plane interlayer translation, which is distinctive among 2D slidetronic ferroelectric materials; and (ii) there is a coexistence of a negative longitudinal piezoelectric effect and an out-of-plane negative Poisson's ratio in the ferroelectric state of bilayer h-BN, which we refer to as anomalous double-negative effects.