MnBi_(2)Te_(4)轴子绝缘态中巨大的非局域边缘导电信号  

Giant nonlocal edge conduction in the axion insulator state of MnBi_(2)Te_(4)

作　　者：李耀鑫 刘畅 王永超 连梓臣 李帅 李昊 吴扬 卢海舟 张金松 王亚愚 Yaoxin Li;Chang Liu;Yongchao Wang;Zichen Lian;Shuai Li;Hao Li;Yang Wu;Hai-Zhou Lu;Jinsong Zhang;Yayu Wang(State Key Laboratory of Low Dimensional Quantum Physics,Department of Physics,Tsinghua University,Beijing 100084,China;Beijing Academy of Quantum Information Sciences,Beijing 100193,China;Beijing Key Laboratory of Opto-electronic Functional Materials&Micro-Nano Devices,Department of Physics,Renmin University of China,Beijing 100872,China;Key Laboratory of Quantum State Construction and Manipulation(Ministry of Education),Renmin University of China,Beijing 100872,China;Shenzhen Institute for Quantum Science and Engineering and Department of Physics,Southern University of Science and Technology,Shenzhen 518055,China;Shenzhen Key Laboratory of Quantum Science and Engineering,Shenzhen 518055,China;Quantum Science Center of Guangdong-Hong Kong-Macao Greater Bay Area(Guangdong),Shenzhen 518045,China;International Quantum Academy,Shenzhen 518048,China;School of Materials Science and Engineering,Tsinghua University,Beijing 100084,China;Tsinghua-Foxconn Nanotechnology Research Center,Department of Physics,Tsinghua University,Beijing 100084,China;College of Science,Beijing University of Chemical Technology,Beijing 100029,China;New Cornerstone Science Laboratory,Frontier Science Center for Quantum Information,Beijing 100084,China;Hefei National Laboratory,Hefei 230088,China)

机构地区：[1]State Key Laboratory of Low Dimensional Quantum Physics,Department of Physics,Tsinghua University,Beijing 100084,China [2]Beijing Academy of Quantum Information Sciences,Beijing 100193,China [3]Beijing Key Laboratory of Opto-electronic Functional Materials&Micro-Nano Devices,Department of Physics,Renmin University of China,Beijing 100872,China [4]Key Laboratory of Quantum State Construction and Manipulation(Ministry of Education),Renmin University of China,Beijing 100872,China [5]Shenzhen Institute for Quantum Science and Engineering and Department of Physics,Southern University of Science and Technology,Shenzhen 518055,China [6]Shenzhen Key Laboratory of Quantum Science and Engineering,Shenzhen 518055,China [7]Quantum Science Center of Guangdong-Hong Kong-Macao Greater Bay Area(Guangdong),Shenzhen 518045,China [8]International Quantum Academy,Shenzhen 518048,China [9]School of Materials Science and Engineering,Tsinghua University,Beijing 100084,China [10]Tsinghua-Foxconn Nanotechnology Research Center,Department of Physics,Tsinghua University,Beijing 100084,China [11]College of Science,Beijing University of Chemical Technology,Beijing 100029,China [12]New Cornerstone Science Laboratory,Frontier Science Center for Quantum Information,Beijing 100084,China [13]Hefei National Laboratory,Hefei 230088,China

出　　处：《Science Bulletin》2023年第12期1252-1258,M0003,共8页科学通报（英文版）

基　　金：supported by the Innovation Program for Quantum Science and Technology (2021ZD0302502);the National Key R&D Program of China (2018YFA0307100 and 2022YFA1403700);the National Natural Science Foundation of China (51991340, 21975140, 11925402, and 12274453);supported by Open Research Fund Program of the State Key Laboratory of Low-Dimensional Quantum Physics (KF202204);supported by the Guangdong Province (2020KCXTD001 and 2016ZT06D348);Center for Computational Science and Engineering of SUSTech;supported by the New Cornerstone Science Foundation through the New Cornerstone Investigator Program and the XPLORER PRIZE

摘　　要：近年发现的反铁磁拓扑绝缘体MnBi_(2)Te_(4)是一种具有多重新奇性质的材料.由于范德瓦尔斯层状结构和层间反铁磁序,这一材料可用于探索在微纳尺度下的器件中独特的拓扑量子现象,比如奇数层MnBi_(2)Te_(4)的量子反常霍尔效应和偶数层的轴子绝缘态.理论预言,MnBi_(2)Te_(4)轴子绝缘态具有独特的螺旋棱态电流,从而产生非局域输运,但目前还没有在实验上观测到.本文报道了少层MnBi_(2)Te_(4)器件中的输运研究,厚度范围从6层到9层.当系统处于轴子绝缘态时,作者观察到偶数层器件的巨大非局域输运信号.而在同样的磁场范围内,奇数层器件的非局域信号几乎为零,结合理论计算,作者发现这种非局域输运是通过分布在侧面与上下表面之间的棱处的螺旋电流实现的,轴子绝缘态中的螺旋棱态电流的观测有助于对宇称反常的半量子化物理的进一步探索,可能在未来的拓扑和量子器件中发挥其独特的重要作用。The recently discovered antiferromagnetic(AFM)topological insulator(TI)MnBi_(2)Te_(4) represents a versatile material platform for exploring exotic topological quantum phenomena in nanoscale devices.It has been proposed that even-septuple-layer(even-SL)MnBi_(2)Te_(4) can host helical hinge currents with unique nonlocal behavior,but experimental confirmation is still lacking.In this work,we report transport studies of exfoliated MnBi_(2)Te_(4) flakes with varied thicknesses down to the few-nanometer regime.We observe giant nonlocal transport signals in even-SL devices when the system is in the axion insulator state but vanishingly small nonlocal signal in the odd-SL devices at the same magnetic field range.In conjunction with theoretical calculations,we demonstrate that the nonlocal transport is via the helical edge currents mainly distributed at the hinges between the side and top/bottom surfaces.The helical edge currents in the axion insulator state may find unique applications in topological quantum devices.

关 键 词：范德瓦尔斯 拓扑绝缘体 量子反常霍尔效应 量子现象 量子化 反铁磁序 宇称 量子器件 

分 类 号：O469[理学—凝聚态物理]