【作者】 张康康； 王聪； 张敏昊； 宋凤麒； 季威； 谢素原；

【Author】 Kangkang Zhang;Cong Wang;Minhao Zhang;Zhanbin Bai;Fang-Fang Xie;Yuan-Zhi Tan;Junming Liu;Guanghou Wang;Fengqi Song;Wei Ji;Su-Yuan Xie;National Laboratory of Solid State Microstructures,Collaborative Innovation Center of Advanced Microstructures,and School of Physics,Nanjing University;Beijing Key Laboratory of Optoelectronic Functional Materials & Micro-Nano Devices,and Department of Physics,Renmin University of China;State Key Laboratory of Physical Chemistry of Solid Surfaces and Department of Chemistry,College of Chemistry and Chemical Engineering,Xiamen University;

【机构】 固体微结构物理国家重点实验室人工微结构科学与技术协同创新中心南京大学物理学院； 光电功能材料与微纳器件北京市重点实验室中国人民大学物理学院； 固体表面物理化学国家重点实验室厦门大学化学化工学院化学系；

【摘要】 此处所说的单分子"铁电"体类似于单分子磁体,是从宏观到单分子的类比。铁电性指的是某一材料存在自发的电极化、并且该电极化在外场作用下可以被翻转的特性。这种自发极化会被外加电场翻转,表现出铁电的电滞回线,可以用来制造铁电存储器。对于有限尺寸的三维铁电体而言,其铁电性是内部电偶极子本征关联耦合的结果,表现出铁电极化。伴随着铁电极化,会存在退极化场,导致铁电内部形成铁电畴,以抵消退极化场。而其内部退极化场与材料的厚度成反比,当材料很薄的时候,内部的极化场会很大,该退极化场反过来作用与铁电极化上,最终导致铁电极化消失,这也就是铁电性的尺寸效应。过去人们将铁电从块体做到薄膜到纳米线,再到纳米点,并在单层二维铁电中也测量到了铁电极化的存在。走到最小,便到达零维了。近期,我们展示了以C₈₂笼中Gd原子位置作为存储介质的一种新型单分子器件。在三端单分子器件中,利用背栅电场的极大（10⁹V/m）调控能力,操控了Gd@C₈₂中Gd原子的吸附位置,使得器件的能级序列表现出了两种状态,实现了可逆双态切换。理论研究表明,C₈₂笼中存在Gd原子的两种可能位置,整个分子类似一个单电偶极的驻极体,背栅电场操控偶极翻转,实质上就是Gd原子位置的切换。该器件便是通过控制Gd原子的位置成功控制了单个分子的电偶极子的方向,实现了单分子"铁电"的器件证明。该器件成功的演示了存储、读取和复位的操作,为未来基于单分子驻极体的存储器件开辟了新方向。更多还原

【Abstract】 The single-molecule "ferroelectric" referred here is similar to single-molecule magnet,it is an analogy from macroscopic to single-molecule.Ferroelectric property refers to the property of a material with spontaneous electric polarization that can be reversed under the action of an external field.Previously,scientists sought for ferroelectricity from bulk to thin film,nanowire and then to quantum dot,and the existence of ferroelectric polarization was already proved in monolayer and two-dimensional ferroelectricity.If the scale goes to the smallest,then to zero dimensions.Recently,we demonstrated a novel single-molecule device using Gd atom’s position in C₈₂ cage as storage medium.In a three-terminal single-molecule device,the adsorption position of Gd atom in Gd@C₈₂ is controlled by using the maximum field（109 V/m） regulating ability of back gate electrode,so that the energy level sequence of the device shows two states and a reversible two-state switch is realized.Theoretical research shows that there are two possible positions of Gd atom in C₈₂ cage.The whole molecule is similar to an electret with a single dipole.The gate electric field controls the dipole flip,which is essentially the position switch of Gd atom.This device successfully controls the direction of the electric dipole of a single-molecule by controlling the position of Gd atom,and realizes the device proof of the single-molecule "ferroelectric".The device successfully demonstrated the operation of storage,read and reset,and paved a new way for future memory devices based on single-molecule electret.更多还原