Title: Emergence of Nontrivial Low‐Energy Dirac Fermions in Antiferromagnetic EuCd ₂ As ₂

Abstract

Abstract 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 EuCd ₂ As ₂ . 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 platformmore » for the quest of topological Dirac fermions in a magnetic system.« less

Authors:

Ma, Junzhang  ^[1];

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Wang, Han ^[2]; Nie, Simin ^[3]; Yi, Changjiang ^[4]; Xu, Yuanfeng ^[4]; Li, Hang ^[4]; Jandke, Jasmin ^[5]; Wulfhekel, Wulf ^[6]; Huang, Yaobo ^[7]; West, Damien ^[2]; Richard, Pierre ^[8]; Chikina, Alla ^[5]; Strocov, Vladimir N. ^[5]; Mesot, Joël ^[1]; Weng, Hongming ^[9]; Zhang, Shengbai ^[2]; Shi, Youguo ^[9]; Qian, Tian ^[9]; Shi, Ming ^[5]; Ding, Hong ^[10]

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+ Show Author Affiliations

1. Paul Scherrer Institute Swiss Light Source CH‐5232 Villigen PSI Switzerland, Institute of Condensed Matter Physics École Polytechnique Fédérale de Lausanne CH‐10 15 Lausanne Switzerland
2. Department of Physics Applied Physics, and Astronomy Rensselaer Polytechnic Institute Troy NY 12180 USA
3. Department of Materials Science and Engineering Stanford University Stanford CA 94305 USA
4. Beijing National Laboratory for Condensed Matter Physics and Institute of Physics Chinese Academy of Sciences Beijing 100190 China, School of Physics University of Chinese Academy of Sciences Beijing 100190 China
5. Paul Scherrer Institute Swiss Light Source CH‐5232 Villigen PSI Switzerland
6. Physikalisches Institut Karlsruhe Institute of Technology 76131 Karlsruhe Germany
7. Shanghai Synchrotron Radiation Facility Shanghai Institute of Applied Physics Chinese Academy of Sciences Shanghai 201204 China
8. Beijing National Laboratory for Condensed Matter Physics and Institute of Physics Chinese Academy of Sciences Beijing 100190 China, School of Physics University of Chinese Academy of Sciences Beijing 100190 China, Institut quantique Université de Sherbrooke 2500 boulevard de l'Université Sherbrooke Québec J1K 2R1 Canada
9. Beijing National Laboratory for Condensed Matter Physics and Institute of Physics Chinese Academy of Sciences Beijing 100190 China, Songshan Lake Materials Laboratory Dongguan Guangdong 523808 China
10. Beijing National Laboratory for Condensed Matter Physics and Institute of Physics Chinese Academy of Sciences Beijing 100190 China, School of Physics University of Chinese Academy of Sciences Beijing 100190 China, Songshan Lake Materials Laboratory Dongguan Guangdong 523808 China, CAS Center for Excellence in Topological Quantum Computation University of Chinese Academy of Sciences Beijing 100190 China

Publication Date:

Mon Feb 24 00:00:00 EST 2020

Sponsoring Org.:

USDOE

OSTI Identifier:

1601506

Grant/Contract Number:  

DESC0002623

Resource Type:

Publisher's Accepted Manuscript

Journal Name:

Advanced Materials

Additional Journal Information:

Journal Name: Advanced Materials Journal Volume: 32 Journal Issue: 14; Journal ID: ISSN 0935-9648

Publisher:

Wiley Blackwell (John Wiley & Sons)

Country of Publication:

Germany

Language:

English