High-precision realization of robust quantum anomalous Hall state in a hard ferromagnetic topological insulator

Cui-Zu Chang; Weiwei Zhao; Duk Y Kim; Haijun Zhang; Badih A Assaf; Don Heiman; Shou-Cheng Zhang; Chaoxing Liu; Moses H W Chan; Jagadeesh S Moodera

doi:10.1038/nmat4204

High-precision realization of robust quantum anomalous Hall state in a hard ferromagnetic topological insulator

Nat Mater. 2015 May;14(5):473-7. doi: 10.1038/nmat4204. Epub 2015 Mar 2.

Authors

Affiliations

¹ Francis Bitter Magnet Lab, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
² The Center for Nanoscale Science and Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802-6300, USA.
³ Department of Physics, Stanford University, Stanford, California 94305-4045, USA.
⁴ Department of Physics, Northeastern University, Boston, Massachusetts 02115, USA.
⁵ 1] Francis Bitter Magnet Lab, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA [2] Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.

PMID: 25730394
DOI: 10.1038/nmat4204

Abstract

The discovery of the quantum Hall (QH) effect led to the realization of a topological electronic state with dissipationless currents circulating in one direction along the edge of a two-dimensional electron layer under a strong magnetic field. The quantum anomalous Hall (QAH) effect shares a similar physical phenomenon to that of the QH effect, whereas its physical origin relies on the intrinsic spin-orbit coupling and ferromagnetism. Here, we report the experimental observation of the QAH state in V-doped (Bi,Sb)2Te3 films with the zero-field longitudinal resistance down to 0.00013 ± 0.00007h/e(2) (~3.35 ± 1.76 Ω), Hall conductance reaching 0.9998 ± 0.0006e(2)/h and the Hall angle becoming as high as 89.993° ± 0.004° at T = 25 mK. A further advantage of this system comes from the fact that it is a hard ferromagnet with a large coercive field (Hc > 1.0 T) and a relative high Curie temperature. This realization of a robust QAH state in hard ferromagnetic topological insulators (FMTIs) is a major step towards dissipationless electronic applications in the absence of external fields.