维格纳晶体的实验观测  

Experimental observations of Wigner crystals

作　　者：高幸 薛禹承 姜宇航 毛金海 Gao Xing;Xue Yu-Cheng;Jiang Yu-Hang;Mao Jin-Hai(School of Physical Sciences,University of Chinese Academy of Sciences,Beijing 100049,China;College of Materials Science and Optoelectronic Technology,University of Chinese Academy of Sciences,Beijing 100049,China;Center of Materials Science and Optoelectronics Engineering,University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]中国科学院大学物理科学学院,北京100049 [2]中国科学院大学材料科学与光电技术学院,北京100049 [3]中国科学院大学材料与光电研究中心,北京100049

出　　处：《物理学报》2024年第24期1-8,共8页Acta Physica Sinica

基　　金：国家重点研发计划(批准号:2019YFA0307800);国家自然科学基金(批准号:12074377);中央高校基本科研业务费专项资金资助的课题。

摘　　要：1934年,就读于普林斯顿大学的Eugene Wigner预言了电子晶体的存在.电子同时具有动能和相互作用的势能,当电子态密度满足一定的条件时,由于电子之间的排斥作用,电子会倾向于按规则的晶格结构排布,形成电子晶体,也称为维格纳晶体.近90年来,维格纳晶体一直吸引着凝聚态物理学家.1979年,实验发现在液氦表面存在从电子液体到电子晶体的相变.之后的实验中观察到在强磁场下的二维电子气中存在二维维格纳晶体的特征.然而,在实空间中直接观测二维维格纳晶体仍然是一项艰巨的挑战.通过WSe2/WS2 moiré超晶格的石墨烯传感层,Li等在实验中观察到了维格纳晶体的实空间形貌.而在最近的研究中,Tsui等使用高分辨率扫描隧道显微镜测量技术,直接对贝纳尔堆叠(Bernal stacking)双层石墨烯中的磁场诱导维格纳晶体进行成像,并研究其结构特性与电子密度、磁场和温度的函数关系.本文将通过4篇代表性工作,简要介绍维格纳晶体的进展和发展前景.In 1934,Eugene Wigner,who was studying at Princeton University,predicted the existence of electronic crystals.Electrons have both kinetic energy and potential energy of interaction.When the density of electronic states satisfies certain conditions,due to the repulsion between electrons,electrons will tend to arrange themselves in a regular lattice structure,forming electron crystals,which is also known as Wigner crystals.For nearly 90 years,Wigner crystals have fascinated condensed matter physicists.Physicists have designed many ingenious semiconductor heterojunctions to obtain lower electron densities and added magnetic fields to achieve larger effective mass of electron.In 1979,experiments revealed the existence of a phase transition from an electron liquid phase to an electron crystal on the surface of liquid helium,and subsequent experiments observed the characteristics of two-dimensional(2D)Wigner crystals in 2D electron gas under high magnetic fields.However,direct observation of 2D Wigner lattices in real space remains a formidable challenge.Through the graphene sensing layer of WSe2/WS2 moirésuperlattice,Hongyuan Li,Feng Wang,et al.observed the real-space morphologies of Wigner crystals in their experiments.And in a recent study,researchers used high-resolution scanning tunneling microscopy to directly image magnetic field-induced Wigner crystals in Bernal stacking bilayer graphene and investigated their structural properties as a function of electron density,magnetic field,and temperature.In this paper,we will introduce some interesting things about Wigner crystals through four representative researches briefly.

关 键 词：维格纳晶体 电子固体 量子相变 扫描隧道显微镜 

分 类 号：O4[理学—物理]