Realization of stable ferromagnetic order in a topological insulator: Codoping-enhanced magnetism in 4f transition metal doped Bi2Se3

Bei Deng, Yiou Zhang, S. B. Zhang, Yayu Wang, Ke He, and Junyi Zhu
Phys. Rev. B 94, 054113 – Published 26 August 2016

Abstract

The quantum anomalous Hall effect (QAHE) originates from a combination of the spin-orbital coupling and the breaking of time-reversal symmetry due to intrinsic ferromagnetic ordering and was recently observed in Cr and V doped magnetic topological insulators (TIs). However, it was only observed at extremely low temperatures due to the low ferromagnetic Curie temperature and the tiny magnetically induced gap. To fully understand the mechanism of the ferromagnetic ordering, thereby improving the ferromagnetism, we investigated 4f transition metal doped Bi2Se3, using density functional theory approaches. We predict that Eu and Sm can introduce stable long-range ferromagnetic states in Bi2Se3, with large magnetic moments and low impurity disorders. Additionally, codoping is proposed to tune the Fermi level into the gap, which simultaneously improves the magnetic moment and the incorporation of magnetic ions. Our findings, thus, offer a step in facilitating the realization of QAHE in TI systems.

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  • Received 20 November 2015
  • Revised 18 July 2016

DOI:https://doi.org/10.1103/PhysRevB.94.054113

©2016 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Bei Deng1, Yiou Zhang1, S. B. Zhang2, Yayu Wang3, Ke He3, and Junyi Zhu1,*

  • 1Department of Physics, The Chinese University of Hong Kong, Hong Kong, China
  • 2Department of Physics, Applied Physics, and Astronomy, Rensselaer Polytechnic Institute, Troy, New York 12180, USA
  • 3Department of Physics, Tsinghua University, Beijing 100084, People's Republic of China

  • *jyzhu@phy.cuhk.edu.hk

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Issue

Vol. 94, Iss. 5 — 1 August 2016

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