Publication detail

Large magnetic gap at the Dirac point in Bi2Te3/MnBi2Te4 heterostructures

Rienks, EDL. Wimmer, S. Sanchez-Barriga, J. Caha, O. Mandal, PS. Ruzicka, J. Ney, A. Steiner, H. Albu, M. Kothleitner, G. Michalicka, J. Khan, SA. Minar, J. Ebert, H. Bauer, G. Freyse, F. Varykhalov, A. Rader, O. Springholz, G.

Original Title

Large magnetic gap at the Dirac point in Bi2Te3/MnBi2Te4 heterostructures

Type

journal article in Web of Science

Language

English

Original Abstract

Magnetically doped topological insulators enable the quantum anomalous Hall effect (QAHE), which provides quantized edge states for lossless charge-transport applications(1-8). The edge states are hosted by a magnetic energy gap at the Dirac point(2), but hitherto all attempts to observe this gap directly have been unsuccessful. Observing the gap is considered to be essential to overcoming the limitations of the QAHE, which so far occurs only at temperatures that are one to two orders of magnitude below the ferromagnetic Curie temperature, T-C (ref. (8)). Here we use low-temperature photoelectron spectroscopy to unambiguously reveal the magnetic gap of Mn-doped Bi2Te3, which displays ferromagnetic out-of-plane spin texture and opens up only below T-C. Surprisingly, our analysis reveals large gap sizes at 1 kelvin of up to 90 millielectronvolts, which is five times larger than theoretically predicted(9). Using multiscale analysis we show that this enhancement is due to a remarkable structure modification induced by Mn doping: instead of a disordered impurity system, a self-organized alternating sequence of MnBi2Te4 septuple and Bi2Te3 quintuple layers is formed. This enhances the wavefunction overlap and size of the magnetic gap(10). Mn-doped Bi2Se3 (ref. (11)) and Mn-doped Sb2Te3 form similar heterostructures, but for Bi2Se3 only a nonmagnetic gap is formed and the magnetization is in the surface plane. This is explained by the smaller spin-orbit interaction by comparison with Mn-doped Bi2Te3. Our findings provide insights that will be crucial in pushing lossless transport in topological insulators towards room-temperature applications.

Keywords

magnetic gap

Authors

Rienks, EDL.; Wimmer, S.; Sanchez-Barriga, J.; Caha, O.; Mandal, PS.; Ruzicka, J.; Ney, A.; Steiner, H. ; Albu, M.; Kothleitner, G.; Michalicka, J. ; Khan, SA.; Minar, J.; Ebert, H.; Bauer, G. ; Freyse, F.; Varykhalov, A.; Rader, O. Springholz, G.

Released

19. 12. 2019

Publisher

NATURE PUBLISHING GROUP

Location

LONDON

ISBN

0028-0836

Periodical

NATURE

Year of study

576

Number

7787

State

United Kingdom of Great Britain and Northern Ireland

Pages from

423

Pages to

441

Pages count

19

URL

https://www.nature.com/articles/s41586-019-1826-7

BibTex

@article{BUT161616,
  author="Rienks, EDL. and Wimmer, S. and Sanchez-Barriga, J. and Caha, O. and Mandal, PS. and Ruzicka, J. and Ney, A. and Steiner, H. and Albu, M. and Kothleitner, G. and Michalicka, J. and Khan, SA. and Minar, J. and Ebert, H. and Bauer, G. and Freyse, F. and Varykhalov, A. and Rader, O. Springholz, G.",
  title="Large magnetic gap at the Dirac point in Bi2Te3/MnBi2Te4 heterostructures",
  journal="NATURE",
  year="2019",
  volume="576",
  number="7787",
  pages="423--441",
  doi="10.1038/s41586-019-1826-7",
  issn="0028-0836",
  url="https://www.nature.com/articles/s41586-019-1826-7"
}