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  4. Emergence of Nontrivial Low-Energy Dirac Fermions in Antiferromagnetic EuCd2As2
 
research article

Emergence of Nontrivial Low-Energy Dirac Fermions in Antiferromagnetic EuCd2As2

Ma, Junzhang
•
Wang, Han
•
Nie, Simin
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February 24, 2020
Advanced Materials

Parity-time symmetry plays an essential role for the formation of Dirac states in Dirac semimetals. So far, all of the experimentally identified topologically nontrivial Dirac semimetals (DSMs) possess both parity and time reversal symmetry. The realization of magnetic topological DSMs remains a major issue in topological material research. Here, combining angle-resolved photoemission spectroscopy with density functional theory calculations, it is ascertained that band inversion induces a topologically nontrivial ground state in EuCd2As2. As a result, ideal magnetic Dirac fermions with simplest double cone structure near the Fermi level emerge in the antiferromagnetic (AFM) phase. The magnetic order breaks time reversal symmetry, but preserves inversion symmetry. The double degeneracy of the Dirac bands is protected by a combination of inversion, time-reversal, and an additional translation operation. Moreover, the calculations show that a deviation of the magnetic moments from the c-axis leads to the breaking of C3 rotation symmetry, and thus, a small bandgap opens at the Dirac point in the bulk. In this case, the system hosts a novel state containing three different types of topological insulator: axion insulator, AFM topological crystalline insulator (TCI), and higher order topological insulator. The results provide an enlarged platform for the quest of topological Dirac fermions in a magnetic system.

  • Details
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Type
research article
DOI
10.1002/adma.201907565
Web of Science ID

WOS:000515180000001

Author(s)
Ma, Junzhang
Wang, Han
Nie, Simin
Yi, Changjiang
Xu, Yuanfeng
Li, Hang
Jandke, Jasmin
Wulfhekel, Wulf
Huang, Yaobo
West, Damien
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Date Issued

2020-02-24

Publisher

Wiley-V C H Verlag Gmbh

Published in
Advanced Materials
Article Number

1907565

Subjects

Chemistry, Multidisciplinary

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Chemistry, Physical

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Nanoscience & Nanotechnology

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Materials Science, Multidisciplinary

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Physics, Applied

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Physics, Condensed Matter

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Chemistry

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Science & Technology - Other Topics

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Materials Science

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Physics

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axion insulator

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condensed matter physics

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higher order topological insulator

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magnetic dirac semimetal

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semimetal

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discovery

Editorial or Peer reviewed

REVIEWED

Written at

EPFL

EPFL units
LMH  
Available on Infoscience
March 8, 2020
Use this identifier to reference this record
https://infoscience.epfl.ch/handle/20.500.14299/167112
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