三角形石墨烯纳米片电子和磁学性质的尺寸效应  

Size-scalingof Electronic and Magnetic Properties of Triangular Graphene Nanoflakes

作　　者：王裔喆 赵国栋 刘超 李永昌[1,2] 刘畅 王音[3] 孔向阳 张培鸿[5] 任伟 WANG Yizhe;ZHAO Guodong;LIU Chao;LI Yongchang;LIU Chang;WANG Yin;KONG Xiangyang;ZHANG Peihong;REN Wei(Materials Genome Institute,State Key Laboratory of Advanced Special Steel,Physics Department,Shanghai University,Shanghai 200444;International Centre for Quantum and Molecular Structures,Shanghai Key Laboratory of High Temperature Superconductors,Shanghai University,Shanghai 200444;Hongzhiwei Technology(Shanghai)Co.Ltd.,Shanghai 201206;Institute of Materials for Mobile Energy,School of Materials Science and Engineering,Shanghai Jiao Tong University,Shanghai,200240;Department of Physics,University at Buffalo,State University of New York,Buffalo,New York 14260)

机构地区：[1]上海大学材料基因组工程研究院,省部共建高品质特殊钢冶金与制备国家重点实验室,物理系,上海200444 [2]上海大学量子与分子结构国际研究中心,上海市高温超导重点实验室,上海200444 [3]鸿之微科技(上海)股份有限公司,上海201206 [4]上海交通大学材料科学与工程学院,汽车动力电池材料研究所,上海200240 [5]纽约州立大学布法罗分校物理系,纽约14260

出　　处：《低温物理学报》2021年第2期115-124,共10页Low Temperature Physical Letters

基　　金：This work was supported by the National Natural Science Foundation of China(51861145315,11929401,12074241);the Independent Research and Development Project of State Key Laboratory of Advanced Special Steel,Shanghai Key Laboratoryof Advanced Ferrometallurgy;Shanghai University(SKLASS2020-Z07);the Scienceand Technology Commission of Shanghai Municipality(19DZ2270200,19010500500,20501130600);High Performance Computing Center,Shanghai University.

摘　　要：基于密度泛函理论,本文研究了氢钝化锯齿形边缘三角形石墨烯纳米片的电子结构和磁学性质,这种石墨烯纳米结构的基态表现出强烈的磁性边缘态和量子尺寸效应。我们应用多种交换关联泛函,对体系的自旋密度和电子结构进行了第一性原理计算和理论分析,结果表明三角形石墨烯纳米片的总磁矩和自旋随尺寸线性变化,平均磁矩随着尺寸变大而增加,并逐渐趋于一个定值。与此同时,体系的能隙随着尺寸增加而减小,其中自旋不变能隙的调控对光学响应和光子激发有着重要意义。计算得到的单电子能谱表明,费米能级的简并度与体系尺寸成正比。应用多种交换关联泛函的计算结果表明,三角形石墨烯纳米片具有可调控的自旋和能隙,为其在纳米级光电器件和磁性半导体的应用方面提供了理论依据.We employ density functional theory(DFT)to investigate the electronic and magnetic properties of hydrogen passivated equilateral triangular graphene nanoflake(GNF).It is predicted that the ground state of such graphene nanostructure exhibits robust magnetic edge states and strong quantum confinement effects.Our DFT calculations based on different exchange-correlation functionals demonstrate that the electronic energy gap and local magnetic moment of GNF s depend sensitively on the GNF size.This is attributed to the different numbers of atoms in the two sublattices of graphene since the spins on the same and different sublattices couple ferromagnetically and antiferromagnetically,respectively.The total net magnetic moment scales linearly with the size of nanoflakes,while the average magnetic moment localized at edges increases and saturates to a constant value for larger sizes.We show that the spin-flipped and spin-preserving energy gaps near Fermi level decrease as the size of GNFs increases.The degeneracies near Fermi energy are proportional to the length of edge in these triangular zigzag-edged GNFs as well.The electronic and magnetic properties of GNFs thus open new avenues for utilizing triangular graphene in nanoscale magnetic semiconductor and optoelectronic devices.

关 键 词：石墨烯纳米片 量子尺寸效应 边界态 密度泛函理论 

分 类 号：O469[理学—凝聚态物理] TQ127.11[理学—电子物理学] TB383.1[理学—物理]