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Published October 2014 | Accepted Version + Supplemental Material
Journal Article Open

Trajectory of the anomalous Hall effect towards the quantized state in a ferromagnetic topological insulator

Abstract

Topological insulators are bulk electronic insulators with symmetry-protected gapless modes on their surfaces. Breaking time-reversal symmetry in these systems via ferromagnetism induces a gapped state characterized by a zero magnetic field quantized Hall response—the quantum anomalous Hall (QAH) state. A key question that has remained experimentally unexplored is the relationship of this new type of quantum Hall (QH) state with the previously known orbitally driven QH states. Here, we show experimentally that a ferromagnetic topological insulator exhibiting the QAH state is well described by the global phase diagram of the QH effect. By mapping the conductivity tensor in the vicinity of the QAH phase, we find evidence for quantum criticality and delocalization behaviour that can quantitatively be described by the renormalization group properties of the QH ground state. This result demonstrates that this QAH state can be understood within the context of the law of corresponding states that governs the QH state.

Additional Information

© 2014 Macmillan Publishers Limited. Received 25 January 2014. Accepted 07 July 2014. Published 17 August 2014. Issue Date October 2014. We are grateful to N. Nagaosa, B.-J. Yang and A. F. Young for fruitful discussions, and M. Nakano, T. Hatano, S. Shimizu, M. Kubota and S. Ono for technical support. This research is supported by the Japan Society for the Promotion of Science (JSPS) through the 'Funding Program for World Leading Innovative R&D on Science and Technology (FIRST Program),' initiated by the Council for Science and Technology Policy (CSTP), and by JPSP Grant-in-Aid for Scientific Research, Nos. 24224009, 24226002 and 25871133. This work was carried out by joint research of the Cryogenic Research Center, the University of Tokyo. Author Contributions: J.G.C. and R.Y. grew and characterized the films. J.G.C., Y.K. and J.F. performed the low-temperature measurements. J.G.C. analysed the data and wrote the paper with contributions from all authors. A.T., K.S.T., M.K. and Y.T. contributed to discussion of the results and guided the project. Y.T. conceived and coordinated the project. The authors declare no competing financial interests.

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Accepted Version - 1406.7450.pdf

Supplemental Material - 41567_2014_BFnphys3053_MOESM5_ESM.pdf

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August 20, 2023
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