Title
Magnetic crystalline-symmetry-protected axion electrodynamics and field-tunable unpinned Dirac cones in EuIn2As2
Publication Date
2-12-2021
Department
Ames Laboratory; Physics and Astronomy
Campus Units
Ames Laboratory, Physics and Astronomy
OSTI ID+
1765424
Report Number
IS-J 10419
DOI
10.1038/s41467-021-21154-y
Journal Title
Nature Communications
Volume Number
12
First Page
999
Abstract
Knowledge of magnetic symmetry is vital for exploiting nontrivial surface states of magnetic topological materials. EuIn2As2 is an excellent example, as it is predicted to have collinear antiferromagnetic order where the magnetic moment direction determines either a topological-crystalline-insulator phase supporting axion electrodynamics or a higher-order-topological-insulator phase with chiral hinge states. Here, we use neutron diffraction, symmetry analysis, and density functional theory results to demonstrate that EuIn2As2 actually exhibits low-symmetry helical antiferromagnetic order which makes it a stoichiometric magnetic topological-crystalline axion insulator protected by the combination of a 180∘ rotation and time-reversal symmetries: C2×T=2′. Surfaces protected by 2′ are expected to have an exotic gapless Dirac cone which is unpinned to specific crystal momenta. All other surfaces have gapped Dirac cones and exhibit half-integer quantum anomalous Hall conductivity. We predict that the direction of a modest applied magnetic field of μ0H ≈ 1 to 2 T can tune between gapless and gapped surface states.
DOE Contract Number(s)
AC02-07CH11358
Language
en
Publisher
Iowa State University Digital Repository, Ames IA (United States)
Supplemental Information
