Intrinsically scale-free ferroelectricity in two-dimensional M_(2)X_(2)Y_(6)  

作　　者：Xin Jin Lei Tao Yu-Yang Zhang Jinbo Pan Shixuan Du 

机构地区：[1]Institute of Physics&University of Chinese Academy of Sciences,Chinese Academy of Sciences,Beijing 100190,China [2]Songshan Lake Materials Laboratory,Dongguan 523808,China [3]CAS Key Laboratory of Vacuum Physics,Beijing 100049,China

出　　处：《Nano Research》2022年第4期3704-3710,共7页纳米研究（英文版）

基　　金：This work was supported by grants from the National Natural Science Foundation of China(No.61888102);the National Key Research and Development Program of China(No.2016YFA0202300);the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB30000000);Computational resources were provided by the National Supercomputing Center in Guangzhou.

摘　　要：Discovery of novel two-dimensional(2D)ferroelectric materials and understanding the mechanism are of vital importance for the design of nanoscale ferroelectric devices.Herein,we report the distinct geometric evolution mechanism of the newly reported M_(2)Ge_(2)Y_(6)monolayers and find out a large group of 2D ferroelectric candidates based on this mechanism.The origination of the ferroelectricity of M_(2)Ge_(2)Y_(6)is the vertical displacement of Ge-dimer in the same direction driven by a soft phonon mode of the centrosymmetric configuration.Interestingly,we find another centrosymmetric configuration which is dynamically stable but higher in energy comparing with the ferroelectric phase.The metastable centrosymmetric phase of M_(2)Ge_(2)Y_(6)monolayers allows a new two-step ferroelectric switching path and may induce novel domain behaviors.Moreover,the ferroelectric M_(2)Ge_(2)Y_(6)monolayers exhibit independently switchable dipoles and maintain their ferroelectricity after contacting with graphene electrodes,indicating their high application potentials in high-density storage.Furthermore,16 ferroelectric(FE)M_(2)Ge_(2)Y_(6)and 65 potential FE M2Sn2Y6 monolayers are identified through high-throughput calculations.Our findings provide a new strategy for future discovery of novel 2D ferroelectric materials and also platforms for experimental design of related functional devices.

关 键 词：two-dimensional(2D)materials mechanism of ferroelectricity scale-free ferroelectricity 

分 类 号：TB3[一般工业技术—材料科学与工程]