Imaging Dirac-mass disorder from magnetic dopant atoms in the ferromagnetic topological insulator Crx(Bi0.1Sb0.9)2-xTe3

被引:223
作者
Lee, Inhee [1 ]
Kim, Chung Koo [1 ]
Lee, Jinho [1 ,2 ,3 ]
Billinge, Simon J. L. [1 ,4 ]
Zhong, Ruidan [1 ,5 ]
Schneeloch, John A. [1 ,6 ]
Liu, Tiansheng [1 ,7 ]
Valla, Tonica [1 ]
Tranquada, John M. [1 ]
Gu, Genda [1 ]
Davis, J. C. Seamus [1 ,8 ,9 ,10 ]
机构
[1] Brookhaven Natl Lab, Condensed Matter Phys & Mat Sci Dept, Upton, NY 11973 USA
[2] Seoul Natl Univ, Dept Phys & Astron, Seoul 151742, South Korea
[3] Inst for Basic Sci Korea, Ctr Correlated Elect Syst, Seoul 151742, South Korea
[4] Columbia Univ, Dept Appl Phys & Appl Math, New York, NY 10027 USA
[5] SUNY Stony Brook, Dept Mat Sci & Engn, Stony Brook, NY 11794 USA
[6] SUNY Stony Brook, Dept Phys & Astron, Stony Brook, NY 11794 USA
[7] North Univ China, Sch Chem Engn & Environm, Taiyuan 030051, Shanxi, Peoples R China
[8] Cornell Univ, Dept Phys, Lab Atom & Solid State Phys, Ithaca, NY 14853 USA
[9] Univ St Andrews, Sch Phys & Astron, St Andrews KY16 9SS, Fife, Scotland
[10] Cornell Univ, Kavli Inst Cornell Nanoscale Sci, Ithaca, NY 14853 USA
基金
英国工程与自然科学研究理事会;
关键词
ferromagnetic topological insulator; Dirac-mass gapmap; Dirac-mass disorder; magnetic dopant atoms; SURFACE; FERMION;
D O I
10.1073/pnas.1424322112
中图分类号
O [数理科学和化学]; P [天文学、地球科学]; Q [生物科学]; N [自然科学总论];
学科分类号
07 ; 0710 ; 09 ;
摘要
To achieve and use the most exotic electronic phenomena predicted for the surface states of 3D topological insulators (TIs), it is necessary to open a "Dirac-mass gap" in their spectrum by breaking time-reversal symmetry. Use of magnetic dopant atoms to generate a ferromagnetic state is the most widely applied approach. However, it is unknown how the spatial arrangements of the magnetic dopant atoms influence the Dirac-mass gap at the atomic scale or, conversely, whether the ferromagnetic interactions between dopant atoms are influenced by the topological surface states. Here we image the locations of the magnetic (Cr) dopant atoms in the ferromagnetic TI Cr-0.08(Bi0.1Sb0.9)(1.92)Te-3. Simultaneous visualization of the Dirac-mass gap Delta(r) reveals its intense disorder, which we demonstrate is directly related to fluctuations in n(r), the Cr atom areal density in the termination layer. We find the relationship of surface-state Fermi wavevectors to the anisotropic structure of Delta(r) not inconsistent with predictions for surface ferromagnetism mediated by those states. Moreover, despite the intense Dirac-mass disorder, the anticipated relationship Delta(r) alpha n(r) is confirmed throughout and exhibits an electron-dopant interaction energy J* = 145 meV.nm(2). These observations reveal how magnetic dopant atoms actually generate the TI mass gap locally and that, to achieve the novel physics expected of time-reversal symmetry breaking TI materials, control of the resulting Dirac-mass gap disorder will be essential.
引用
收藏
页码:1316 / 1321
页数:6
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