多层六方氮化硼中铁电调控的力电耦合

Ferroelectricity-mediated electromechanical coupling in boron nitride multilayers

近期在范德华材料中发现的滑移铁电性因其具备在原子厚度上实现微型功能器件的潜力而引起了广泛的兴趣.然而,由于元件层间的范德华耦合相对较弱,导致固有的电极化强度较低,在很大程度上制约了该性质的实际应用.我们以多层六方氮化硼(h-BN)为例,采用从头算方法,发现施加垂直压力可以显著增强滑移铁电性.在4.63 GPa的中等压力下,双层和三层h-BN的极化强度分别提高了125.58%和104.79%.此外,当弯曲多层h-BN材料时,铁电可以与挠曲电进一步耦合,从而产生更大的电极化.值得注意的是,这一具有的压力增强电极化效应的铁电性可以在无需外加电场的情况下调节弯曲双层h-BN的带隙.这些结果凸显了滑移铁电性可作为一种新的自由度来调控范德华材料中的力电耦合.

The recent discovery of sliding ferroelectricity in van der Waals(vdw)materials has attracted tremendous interest owing to its potential for miniaturizing functional devices with atomic thicknesses.However,the practical applications of this intriguing property are largely hindered by its inherently small electric polarization resulting from weak vdW coupling between the component layers.Using boron nitride(BN)multilayers as a prototype,our ab initio calculations demonstrate that vertical pressure can substantially enhance sliding ferroelectricity.Specifically,a moderate pressure of 4.63 GPa can increase the electric polarization by 125.58%in bilayers and 104.79%in trilayers.Furthermore,when the multilayers are bent,the ferroelectricity can be further coupled with flexoelectricity to yield an amplified net polarization.Notably,the pressure-enhanced electric polarization of ferroelectricity can narrow the band gap of bent BN multilayers without requiring an external electric field.These findings present sliding ferroelectricity as a novel degree of freedom formanipulating electromechanical coupling invdWmaterials.